To please someone is to give them pleasure or to make them happy. This is also a word for polite requests like, "Could you please pass the milk?"
Have you ever been asked "What's the magic word"? It's please, a small word that makes any request more polite. Saying please is sure to please just about everyone, although different things please different people. Turning in your homework on time will please your teachers, while a good belly rub and some extra treats will please your dog.