"Why are you silent?"
Translation:Mengapa kamu diam?
Diam, this word used when someone not talking, animal won't make any sound or a thing did'nt make any sound. We can use this word when we want to order someone to be quiet.
Sepi, it means there's no crowd or sound in a place, for eaxample, when we come into a house but there is no one live in there, it calls 'sepi'. ex: Oh rumah ini sepi sekali! Translation: Oh, This house really silent!
i'm indonesian, but i'm confused how to explained it, hahaha, i hope it's help you to learn bahasa indonesia