What does 'cuales son tus pasatiempos favoritos?

It means 'What is your favourite activity?' so you'd begin:

'Mi actividad favorita es..../Me gusta....' (My favourite activity is.../I like....)

adding whatever is your favourite activity, e.g.

....dormir(sleeping)/comer(eating)/beber(drinking)/leer(reading)/escribir(writing)

hacer compras(shopping)/andar(walking)/correr(running)/nadar(swimming/jugar a....(playing (at)....)

futbol(football)/tenis(tennis/voleibol(volleyball)

viajar(travel)

etc.,etc.,etc.