@SteelWool git is a version management system. Think of it as a diary for your code. GitHub for example, is the Twitter for your code. You use the git system to keep track of your code and all the changes that happen to it, which is really neat.
@MySpaceEmoCat @SteelWool
so yeah, in a bit more detail, Git is a system which basically lets you create savestates for your work, so you can 1. keep track of what you've done and when (if you use commit comments properly) and 2. revert your work to a known good state if you fuck something up
you can even branch your code if you want to try something experimental without fucking up your main development branch, and then if things work out, you can merge the changes back into your main branch