"The man speaks in Korean."
Translation:남자가 한국어로 말합니다.
말아요 (말다) means "don't" or "stop", for example 웃지 말아요 = don't laugh. (To use this: verb stem + 지 + 말아요)
말해요 (말하다) is a simple verb that means "to speak". (말= word, speech, 하다/해요 = to do) For example, 저는 말해요 = I speak.
I'm sorry for my bad English, but I hope this still helped! :)