"What subject do you like?"

Translation: Pelajaran apa yang kamu suka?

[Chuck919019]

"Apakah pelajaran kamu suka"...?

[Pak_John]

I get where you're coming from but... no, that's not right

I would say "yang mana pelajaran kamu suka?" or "Apakah pelajaran kamu paling suka?"

(Apakah like a word which informs the listener that the following sentence is a question)