SweetSaber is a mod manager, for a game called Beat Saber (i guess you already knew that).
It is meant to be as user-friendly as possible, remembering which mods you've installed or used and for what previous versions of a game, in case there is a game update.
Also, yes, this repo is currently unlicensed, we aware of that and everything that comes after it (go look https://choosealicense.com/no-permission)