Yes, they do have something to do with spells. You need to give it to someone who can cast that type of spell. Then you need to right-click on it, and choose invoke. You now have that spell added to your spellbook.

There are four special books (Fire, Earth, Wind, Water) which you need to become a Zen master. All the other books are an easy way to learn spells. However they will only work with a character who is allowed to learn that spell anyway. Right click on the book and if the INVOKE button appears then that character can learn the spell.

I think i have figured out how most things work in this game but one
thing i don't know about is books. I notice they sometimes share names
with spells. Is it possible to somehow use these books to learn spells?
Or are books used for a totally other purpose (besides the ones used
in quests and such). I must have overlooked something that explains
what they do. Any help is appreciated.