Learn French: Les livres sont pour elles.

In French, elles does double duty! You probably know it as a subject pronoun meaning "they" for an all-female group. But it is also used as a stressed pronoun meaning "them" when it comes right after a preposition like pour (for), avec (with), or de (of).

What if the books were for a group of men? Would I use ils?

No, you wouldn't use ils here. The word ils is only used as a subject pronoun (the one doing the action). After a preposition like pour, you must use a stressed pronoun. For an all-male or mixed-gender group, the stressed pronoun for "them" is eux. So you would say: Les livres sont pour eux.

Could I say "Les livres sont pour leur"?

No, though this is a very common mix-up! The word leur is used for "them", but only when it acts as an indirect object pronoun placed directly before a verb (like je leur parle = I speak to them). When "them" follows a preposition like pour, you must use the stressed pronouns elles or eux.

Do I pronounce the "s" at the end of livres and elles?