These words describe something that is attractive, nice to look at.
The word beautiful is stronger and more complete. You could describe a spectacular sunset as beautiful, or a very attractive woman in a fancy dress as beautiful.
The word pretty is more informal and superficial. A nice arrangement of flowers could be described as pretty. You can also describe girls, women, and clothing as pretty – but it is not as strong as beautiful.
The word cute is also informal, and means something is attractive in an adorable way. It is often used for children and animals. When describing an adult (man or woman) as cute, it means the person is attractive, but not SUPER attractive (for
super attractive we would say the person is beautiful/gorgeous – for a woman -handsome – for a man – or hot, has a sexy connotation, for both women and men).
For boys and men, we don’t use pretty or beautiful – we can use handsome (usually for men), hot (also for men) or cute (usually for boys).