Git is a type of version control software that allows tracking to occur within within and among documents of a given project. If this sounds vague, it may be easier to think of Word's 'track-changes' setting. Track changes allows Word users to make comments, edits, etc. that are recorded and highlighted in the word program. Git provides a similar function, but for individual documents and specific files. So, instead of having several versions of a manuscript each with a co-author's initials at the end of the document, Git sort of does this automatically by tacking anyone who is working from the same file. Now, maybe this isn't an issue if you don't create may versions of a document or are content with the 'initial system', but for anyone writing and revising things on a regular basis - like an R script - Git is likely to be very useful. This is especially true for anyone working on group projects, which is increasingly the case in science (there is a general trend for more authors per manuscript through time).
Git also makes sense from an ethical perspective particularly for scientist. Git repositories, like Github, are ideal centralized locations to store code, which allow others to vet, learn, or contribute to existing code.
Of course, this is my naive perception of if git so far and other's have spent a lot more time developing introductions to git and Github.(It's also worth mentioning that Github is one of several cloud Git repositories), Anyways, I figured I'd include some resources for learning about how to use Git, Github, and their integration with RStudio below for myself and others that may be interested.
A good video tutorial of how to use terminal to upload and download items from a Github repository directly to your computer:
Two websites with similar information about using Git Github and Rstudio (I honestly found the video about more effective):
For uploading large files to Github: