So, from what I can tell in your image, your setup is as follows:
/dev/sda1 is a system diagnostics partition, probably accessed by some function in your system's BIOS if you need to put it into recovery mode.
/dev/sda2 ("OS") is an image of how the system was when it left the factory. It's not mounted, but can be used to restore your PC to factory settings if needed (again, probably from some functionality in the BIOS)
/dev/sda3 is the partition Ubuntu is actually installed to (hence being mounted as
/dev/sda4 is an extended partition; this comes about due to a limitation in some filesystems that means they only recognise four partitions. An "extended" partition works sort of like a folder for storing more than this number. (At least, that's how I understand it. This is used here only to store
/dev/sda5 is your swap, which essentially acts in the same way as Windows' paging. It provides the system with virtual memory, and allows you to hibernate the system. I'd say it's excessively large here (beyond a couple of gigabytes of physical RAM you probably only need swap >= total RAM), but having more never hurts if you're using the computer for anything memory-intensive.
unallocated, this is space on the disk which hasn't been assigned to any partition, and won't be used (there'll almost always be a little left over after partitioning, but 1MB out of ~500GB is nothing worth losing any sleep over)
So, to put it briefly: yes your laptop has come with partitions - but the only one that anything will actually be stored on is
/dev/sda3. If you're really desperate to, you could probably reinstall Ubuntu and repartition so that your
/home folder was on a different partition to
/, but to be honest I don't see this as being at all necessary.