simply lists all files and folders at the current location. This includes hidden files. Hidden files usually aren't shown by file browsers (like nautilus which you probably use).
Such files start with a dot (.) or and with a tilde (~). The latter are also called backup files. They are created by most text editors (like gedit which you probably use) automatically and contain the content of the file before the last edit. So you can always go one step back.
I don't recommend it but if you want, you can disable this in gedit by going to Edit → Preferences → Editor and uncheck "Create a backup copy of files before saving".
You can also show this files in nautilus by pressing ctrl+H or going to View and check "Show Hidden Files".