This resourcepack adds (well, re-adds) better quality sounds to the LightWithin Mod, which cannot be included inside the jar anymore due to their size! (They still are pretty much half the size of the whole jar)
And well, that's it. It won't do much without said mod for the Fabric Loader.
Interestd in what the mod is about? Well, it adds a new mechanic called "InnerLights" which are special powers and abilities unique to each and every player (they are based on their UUID, which is kinda of their DNA or something like that!) and can be activated when the player is an dangerous situation, like being surrounded by a bunch of zombies, like this: https://youtu.be/wSgwGm3vVlA