"How are you?" is a nice question. It's a friendly way people in the United States greet each other. But "How are you?" is also a very unusual question that often doesn't have an answer.
When a person meets a friend on the street and asks "How are you?", he only expects to hear the answer "Fine." even if the other person isn't! The reason is that "How are you?" isn't really a question and "Fine." isn't really an answer. They are simple ways of greeting people and saying "Hello".
Sometimes, people also don't say directly what they mean. For example, when someone asks "Do you agree?", the other person might be thinking "No, I disagree." But it isn't very polite to answer so directly, so the other person might say. "I'm not so sure." It's a nicer way to say that you don't agree with someone.
People also don't say directly what they are thinking when they finish conversations with others. For example, many conversations over the phone end when one person says, "I've got to go now." Often, the person who wants to hang u gives an excuse: "Someone's at the door." "Something is burning on the stove!" The excuse might be real, or it might not be. Perhaps the person who wants to hang up simply doesn't want to talk any more, but it isn't very polite to say that. The excuse is more polite, and it doesn't hurt the other person's feelings.
Whether they are greeting each other, talking about an opinion， or ending a conversation, people often don't say directly what they are thinking. It's an important way that people try to be nice to each other, and it's all part of the game of language!
