Why aren’t you saying anything?
In the given sentence, “Warum sagen Sie denn nichts?”, the word “denn” is a modal particle that adds emphasis or emotion to the sentence. It can be translated to “then” in English. Modal particles are common in German and are used to convey the speaker’s attitude or mood. In this case, “denn” adds a sense of urgency or impatience to the question. The sentence can be translated to “Why aren’t you saying anything then?”.