Questions & Answers about Ti riporto il libro domani.
Ti is the unstressed object pronoun for you in the singular, here meaning to you.
So in Ti riporto il libro domani, ti tells you who receives the book back: I’m bringing the book back to you tomorrow.
A native English speaker often expects something more like to you, but Italian usually uses a short pronoun before the conjugated verb:
- Ti porto il libro = I bring the book to you
- Ti scrivo = I write to you