In sociology, a mechanism is like a little engine that works behind the scenes to make things happen. Just like how a car has an engine to make it go, sociologists believe that social systems and events also have little engines that make them work.
For example, let's say you're part of a group of kids playing at the park. Your group might have a mechanism that helps decide who gets to pick the game you're going to play next. Maybe you take turns or maybe there's a leader who decides. Whatever it is, this system is a mechanism that helps your group make decisions.
Sociologists use mechanisms to understand how social processes work. By identifying the different mechanisms that make up a system, they can better understand how that system functions and how it might change over time. It's kind of like taking apart a toy to figure out how it works, but instead of a toy, sociologists are taking apart society to figure out how it works.
In short, mechanisms in sociology are little engines that make social systems and events work. By understanding these mechanisms, sociologists can better understand how society functions.