Personality tests are really big. One of the most mentioned being Myers-Briggs 16 personalities. The benefit of knowing your “exact personality” is that you can tell people that you’ve taken the test and watch videos poking fun at your personality type! XD However it can help you and others understand how you think and respond which can theoretically help them relate to you better.
For me, I think that its best to look at it as a tool, not as an unchanging fact. My personality has changed a lot since my youth and knowing my personality hasn’t actually provided additional insight or lasting relationships. Its more of a novelty, just like knowing my Hogwarts house. 😉
If you are interested in giving it a go, be prepared to answer a lot of questions! XD