So, for a bit of a crash course, a virtual machine is just that, a machine that is virtualized. So, anything you can do with your physical machine (your computer) you can do on a virtual machine. (You could even dual or triple [or more] boot a VM)
Just like a normal computer, changes made to a virtual machine are persistent unless you configure them not to be. So no need to worry about losing changes. (Though, I would suggest taking a snapshot of your newly installed distro as soon as you finish the initial installation, it will be useful if you need a clean starting point for something you want to do)
I suggest you download a couple of Linux distros you want to play with, download VirtualBox, and setup a virtual machine for each distro. You can also setup the VM to run in full screen mode, so it feels like native.
There are tons of guides online to help you out, and a large number of computer nerds here that will help you too.
The one limitation with VMs is gaming. You can get around that limitation once you’re more well versed with them, but just don’t expect to be gaming on a VM for quite a while.