On Windows you have drives C, D, etc, on Linux everything is inside the root folder (i.e. /), and you can mount different partitions or even disks anywhere, so / can be the second partition on your M.2, /boot be the first partition formatted as vfat, /home be on an SSD and /home/nibodhika/hdd be an internal HDD. After you set it up (which you can do during most of the distros graphical installation) it will feel as if those are all just folders, but the important part is that if you ever format one of them the other remain intact. So for example if you have the setup I described above and you format and change your entire Linux distribution, that should only affect the M.2 disk, so the home and HDD are intact, which means that if you set the new distro to mount things in the same place you’ll have all of your configurations and media in place (all you need to do is reinstall the programs you use)