Superficial charm is when someone acts really friendly and nice towards you, but they might not really mean it. It's like when a kid at school compliments your drawing because they want to borrow your markers, even though they don't really care about your drawing.
Some people use superficial charm to make other people like them or to get them to do things for them. It can be easy to fall for someone's charm, but it's important to learn to spot when someone is just being superficially charming and not genuinely interested in you or your well-being.