I'm training to become a software developer with Turing School of Software and Design, and this is what I know about Git so far. I hope it helps!
Git is a version control system. As such, it allows a software developer or (better) a group of developers to keep track of different versions of the software (or other digital project) they are developing. Developers can use Git to take snapshots of the files involved in the project (called "commits") with associated messages describing the changes made since the last snapshot. This allows them to keep track of changes, roll back to old snapshots if things aren't working, and have a framework for building a workflow around. This all takes place in a specific directory (i.e., a folder and its sub-folders) where Git is "initialized," which is called a "local repository" ("repo" for short).
When combined with an online repository service, typically GitHub, developers can "push" (upload) or "pull" (download)