How to can you explain in one sentence why Kwisatz Haderach is related to questions, riddles and answers?

Kwisatz Haderach, a term from Frank Herbert's Dune, is associated with questions, riddles, and answers because he possesses a heightened consciousness and ability to access all memories, allowing him to solve complex problems and see the outcomes of different choices.

Didn't he was able to predict the future hence give possible answers what will happen?

Yes, Kwisatz Haderach's heightened consciousness also allowed him to access future memories and see different possible outcomes, giving him the ability to predict the future and provide answers to complex questions and riddles.