Cuantos hermanos tienes

Literally, on its face, it means, "How many brothers do you have?" But implicit in the Word hermanos (and the question itself) is the Word hermanas. So what the question is really asking is, "How many brothers and sisters do you have?" An answer revealing the number of sisters in one's family as well as brothers would not be unexpected. In Spanish questions, there is usually an accent on the adverbial question Word; in this case, ¿cuántos?