We share code via code "repositories" we call "repo"s for short, so you got that one right.

Git is a version control tool that is used for pushing and pulling changes to code between repos. The repo has to be a "git" repo for it to work. There are other software repos like cvs, sccs, mercurial, bazaar, and more but the vast majority of developers today use 'git' because it is very good -- written by Linux Torvalds (Larry Wall, Junio Hamano, others) who started Linux.