If you’re respectful, you show consideration and regard for someone or something. Be respectful of your neighbors and turn down your disco music when it gets late.
Respectful is the adjective form of the common word respect, which means a feeling of admiration. So when you behave in a way that’s respectful, you’re doing something to show admiration for another person. You might sit in respectful silence when your teacher enters the room. You can be respectful of situations as well as people. You might be respectful of the democratic process and not complain about not winning your school election.