u/Hyss96

Hey! I was riding to work one day and my marlin 7 bike started to brake by itself when going to work, and I saw that this ”pin” was loose. The bike didnt work after this and ive tried to just put it back but it doesnt sit there and bike wont work, any suggestions what it does and how it can be fixed?

If its easy enough to fix by myself or I should leave it for service 🥸
Thanks!