Okay kiddo, have you ever heard the word "trivial"? It means something that is not important or significant.
When we talk about measures, we mean a way of figuring out how big or important something is. A trivial measure is a way of measuring something that is not really important or interesting.
Let me give you an example. Let's say we want to measure how many hairs are on a person's head. That's a pretty basic measure and it can be important for things like creating wigs or determining hair loss. But if we were to measure how many white hairs there are on a person's head, that might be considered a trivial measure because it doesn't really tell us much about the person's health or appearance.
So, in summary, a trivial measure is a way of measuring something that is not very important or insightful.