Literal translation : Do you think my word doesn't sound like a word? The literal translation may fail to deliver the meaning as it is kind of Korean idiom. 내 말이 말 같지가 않아? This can be heard from our parents or bosses when we did something wrong even though they already advised or told us to do something in the right way. So, it's the situation where they get upset. There would be several ways to say it in English. I would say "Don't you understand what I told you already?", "How dare you ignored what I told you?"