BlockCore is a library that allows people to easily add custom blocks to their datapacks. The datapack does not do anything on its own, but rather must be used in combination with another datapack that adds the blocks. If you are downloading this datapack, it's probably because another datapack requires it, or you want to develop one of your own.
I'll add a link to a documentation soon (once I'm done writing it) so you can use this as a dependency for your own datapacks, but I had to push this out in order to release another one of my datapacks that depends on it.
Major thanks to Admin from WASDBuildTeam, who made the custom blocks engine that I based this off of.