Answer: It depends on how the word is being used.
Qué as "what": Most of the time, in a variety of uses, qué is a good translation for "what." Here are a few examples:
- ¿Qué hora es? What time is it?
- ¡Qué mujer! What a woman!
- ¿Qué is la verdad? What is the truth?
- No sé qué hacer con mi vida. I don't know what to do with my life.
- ¿Qué es la ONU? What is the U.N.?
- ¿Qué pasa? What's happening?
- ¿Cuál prefieres? Which one (what one) do you prefer?
- ¿Cuáles prefieres? Which ones (what ones) do you prefer?
- ¿Cuál vas a comprar? Which one (what one) are you going to buy?
- ¿Cuál es el problema? What is the problem? (Literal translation: Which problem is the problem?)
- ¿Cuál es su motivación? What is his motive? (Literally, which motive is his motive?)
- ¿Qué (cuál) manzana prefieres? Which apple (what apple) do you prefer?
- ¿Qué (cuáles) camisas vas a comprar? Which shirts (what shirts) are you going to buy?
- Lo que me dijo es una mentira. What (that which) he told me is a lie.
- Lo que me enoja es su actitud hacia mi madre. What (that which) makes me mad is his attitude toward my mother.
- ¡Cómo! No lo creo. What! I don't believe it.
- ¡Cómo! No puede ser. What! It can't be.
- ¿Cómo? What did you say?

