Joining the student union/society, especially the student union, can improve your interpersonal skills, organizational skills and social skills. You can also add something to your resume in the future to enrich your resume, so that perhaps HR can see your work ability. Suppose you interview a person with similar resume content and business ability, then you have this item and others don't, which will definitely make you stand out in the interview. And you will gain some things that you can't learn as a student union member in the course, such as self-confidence, communication ability, language organization ability and so on. More importantly, joining the student union will be of great help to you in awarding prizes and joining the party.
But at the same time, you should consider that students' union and clubs will occupy a part of your spare time more or less. There is no doubt that I did not join the student union, but joined a self-management Committee, which was more relaxed than the student union. However, sometimes I still feel at a loss. You may have to do these jobs when others are learning various skills and professional courses. There are many such examples in our class. Although I joined many departments of the Student Union, my professional achievements were not outstanding.
So you should consider all aspects comprehensively and make the right choice. In a word, I suggest you join, which can exercise your abilities in many aspects, but you must be competent and don't put too much pressure on yourself, otherwise you will be very tired. I hope it helps you.