Can someone help me understand what I'm looking at and how and what I should use to expand my storage for my Ubuntu OS on my dual boot laptop

Question

I have 2 drives one that shipped with my laptop and another I pulled from my old laptop that previously had Ubuntu on it. It's a few years old but I would like to extend my storage so I can stop getting the low disk storage message and then I can use my laptop for more school work and to help me start learning python. Is there any resources I can use to better understand how my Linux OS uses storage and how to better read and understand what I'm seeing here?

Disk /dev/loop0: 9.7 MiB, 9510912 bytes, 18576 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop1: 8.54 MiB, 8945664 bytes, 17472 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop2: 97.72 MiB, 102445056 bytes, 200088 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop3: 97.6 MiB, 101777408 bytes, 198784 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop4: 55.33 MiB, 58007552 bytes, 113296 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop5: 54.97 MiB, 57614336 bytes, 112528 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop6: 57.33 MiB, 60108800 bytes, 117400 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop7: 57.42 MiB, 60194816 bytes, 117568 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/nvme0n1: 238.49 GiB, 256060514304 bytes, 500118192 sectors
Disk model: INTEL SSDPEKKW256G7                     
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: EFA94F34-B396-44F6-9FEA-937E13C836EA

Device             Start       End   Sectors   Size Type
/dev/nvme0n1p1      2048    206847    204800   100M EFI System
/dev/nvme0n1p2    206848    239615     32768    16M Microsoft reserved
/dev/nvme0n1p3    239616 498006015 497766400 237.4G Microsoft basic data
/dev/nvme0n1p4 498008064 500105215   2097152     1G Windows recovery environment


Disk /dev/sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: ST1000LM014-1EJ1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x9aa4dd4d

Device     Boot      Start        End   Sectors   Size Id Type
/dev/sda1  *          2048     718847    716800   350M  7 HPFS/NTFS/exFAT
/dev/sda2           718848  975417991 974699144 464.8G  7 HPFS/NTFS/exFAT
/dev/sda3        975419392  976961535   1542144   753M 82 Linux swap / Solaris
/dev/sda4        976963582 1953523711 976560130 465.7G  5 Extended
/dev/sda5        976963584 1016023039  39059456  18.6G 83 Linux
/dev/sda6       1016025088 1953523711 937498624   447G 83 Linux

Partition 4 does not start on physical sector boundary.


Disk /dev/loop8: 217.92 MiB, 228478976 bytes, 446248 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop9: 162.89 MiB, 170778624 bytes, 333552 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop10: 44.9 MiB, 47063040 bytes, 91920 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop11: 161.42 MiB, 169254912 bytes, 330576 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop12: 62.9 MiB, 65105920 bytes, 127160 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop13: 144.98 MiB, 151998464 bytes, 296872 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop14: 144.25 MiB, 151248896 bytes, 295408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop15: 290.45 MiB, 304545792 bytes, 594816 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop16: 50.69 MiB, 53133312 bytes, 103776 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop17: 133.1 MiB, 139472896 bytes, 272408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop18: 202.92 MiB, 212758528 bytes, 415544 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

EDIT: This is what is shown when I use df -h. Definitely shows me more information and how my system is storing everything.

df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            7.8G     0  7.8G   0% /dev
tmpfs           1.6G   91M  1.5G   6% /run
/dev/sda5        19G   15G  2.8G  85% /
tmpfs           7.8G  299M  7.5G   4% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           7.8G     0  7.8G   0% /sys/fs/cgroup
/dev/loop0      9.2M  9.2M     0 100% /snap/canonical-livepatch/95
/dev/loop3       98M   98M     0 100% /snap/core/9993
/dev/loop1      8.7M  8.7M     0 100% /snap/canonical-livepatch/90
/dev/loop2       98M   98M     0 100% /snap/core/10126
/dev/loop4       56M   56M     0 100% /snap/core18/1885
/dev/loop5       55M   55M     0 100% /snap/core18/1705
/dev/loop6       58M   58M     0 100% /snap/discord/112
/dev/loop7       58M   58M     0 100% /snap/discord/115
/dev/loop8      218M  218M     0 100% /snap/gnome-3-34-1804/60
/dev/loop9      163M  163M     0 100% /snap/gnome-3-28-1804/145
/dev/loop10      45M   45M     0 100% /snap/gtk-common-themes/1440
/dev/loop11     162M  162M     0 100% /snap/gnome-3-28-1804/128
/dev/loop12      63M   63M     0 100% /snap/gtk-common-themes/1506
/dev/loop13     145M  145M     0 100% /snap/notepadqq/855
/dev/loop14     145M  145M     0 100% /snap/notepadqq/841
/dev/loop15     291M  291M     0 100% /snap/vlc/1700
/dev/loop16      51M   51M     0 100% /snap/snap-store/481
/dev/loop17     134M  134M     0 100% /snap/notepadqq/115
/dev/loop18     203M  203M     0 100% /snap/vlc/1397
/dev/sda6       440G   52G  366G  13% /home
tmpfs           1.6G   24K  1.6G   1% /run/user/127
tmpfs           1.6G   84K  1.6G   1% /run/user/1000
/dev/sda2       465G  303M  465G   1% /media/USER/HP_LNX
/dev/nvme0n1p3  238G   94G  144G  40% /media/USER/Acer

Answer 1

A better way to understand disk space usage is to use the handy app Disk Usage Analyzer, or to use df -h and du -h, which will show you disk usage by different volumes and files. The main drives you are concerned about are those beginning with /dev/sd. These are physical drives in your system (or partitions if they have a number at the end).

If you would like to "extend your disk space" to another drive, you can look at RAID (to increase the size of your entire root filesystem, ans share the used space among both drives, allowing you to expand every folder). You could also simply plug in another hard drive and use it as such. For example, just store all your big files or python projects there (it would be mounted in /media by default, but this can be changed; see link below.). Another solution would be to move your home folder to another drive. Copy your files to another drive, and then set the other drive to mount in /home/username (see https://www.man7.org/linux/man-pages/man5/fstab.5.html). This would put everything in ~ (Desktop, Downloads, Documents, etc) on your second hard drive.

EDIT For understanding loop devices, see here.

EDIT 2 The output you added from df -h shows that you have two separate partitions: one for /, and one for /home. You have plenty of disk space available in /home, which contains your Desktop, Documents, etc. You may be able to shrink this partition and allocate more to the rest of the system, but that would be a different question (that has probably already been answered).