なんてかわいい子犬！！ What a cute puppy!! 今日はなんていい天気だ！ What great weather (we have ) today. あなたはなんて不注意なひと。 You are such a careless person. なんて　can be used to exaggerate a certain aspect of a sentence or the sentence as a whole. It can apply to " What a ..... " and " such a " if translated in English. It can apply for both positive exaggerations and negative exaggerations.