There are some really old introductory unix texts of how the system is structured and why, 99% of this stuff is still true for most linux (except some weird experimental alternatives where people tried to create ms-unix ). The basic terminal commands should also be useful, and help you understand. For example open a terminal and see the command for copy (cp) or (mv) or mkdir rm rmdir and use -h for the help of the options of each (if -h doesn't work then --help does) and then extensive documentation is found by name of command after "man" for manual ex: man chmod

One of the most magical things that happens in unix is mount, where you create a directory (mount point /mnt), take a device like your usb stick volume named sdb1

mount /dev/sdb1 /mnt

ls -lah /mnt

say you create /tmp/disks and in it a b c d e and mount 5 disks in a through e and it appears as one subdirectory /tmp/disks

Instead of looking at a file browser and something going cling-clong and appearing as a volume, what dumb people do