【How-to】How do you use under in japanese

何ですか means “What is it?” or “What?” And breaks down as: 何 (なん, nan “what”), (です, desu “it is” -> “is it”), (か, ka, question particle, i.e. it makes the sentence into a question). It is more polite/formal than 何 alone, when it is pronounced なに (nani).