Translation:What is your passion?
I agree with WayangOrang that Nafsu it closer to lust than Gairah, but also worth mentioning that Nafsu is a particularly interesting word that is broader than "Lust" in English. Lust in English seems to be confined to primarily sexual context where Nafsu is not limited like this. I have seen it (as in the KBBI example) used in reference to food, referring broadly to any kind of physiological reaction to a stimulus. Similar I suppose to "Enak" which means much more than just "tasty", more like "physically pleasing". Nafsu can be used to describe any physical desire, for food, beauty etc. Interesting word for sure. Gairah is more of a strong interest in doing something not necessarily of a sexual nature.
Yes, "lust" is typically used as "improper sexual desire" in English nowadays, but historically I don't think that's what it always meant. It may have been used more broadly for strong desires of other kind. Some semantic narrowing has taken place for the word.