What practical and cool knowledge do boys need to learn?

I recommend you to learn the piano. I personally like playing the piano very much. At first, I felt that the piano was particularly artistic, and a good tune always made people feel happy. Most importantly, it will make a person gradually become particularly quality and polite. For example, a piano master sitting there playing the piano has an invisible attraction. When he plays a good tune, people feel particularly envious and admired. If conditions permit, I really recommend you to learn.