If you know what word Lore" means, you're halfway there. If you don't, then you won't be there even if I tell you. The lore here is the game world, it's (I stress this one) history, it's present, it's gods, religions, cultures... It's what the world is. When the game (or a book, a movie...) is not set in "our" world, the lore is defining what the world is. Lore is the general knowledge about the world. Ok