"The coat does not have buttons."
Translation:Rocken har inte knappar.
It is correct to say. The meaning is the same in some ways but the word "några" is obviously missing... "some". If somebody asked me about the design of this coat I would maybe answer The coat has no buttons. If someone asked why I had my coat open in that strange way I would answer "Rocken har inte några knappar" The first is more of a statement, a definite fact. Yours is more an answer to some question you or somebody else may ask.