Quantum triviality is like playing with building blocks at your age. Think of building blocks like tiny, tiny particles that you can put together in different ways. Now, imagine that you have a very big block made up of lots of these tiny particles.
When scientists study these tiny particles, they try to understand how they behave together in the big block. Sometimes, they can describe the behavior of the big block using a rule or equation that tells them how the tiny particles work together.
However, sometimes they can't easily find this rule and it becomes very hard to predict how the big block behaves. This is called a "non-trivial" system.
Quantum triviality is when scientists can find a simple rule or equation to describe the behavior of the big block made up of tiny particles. In other words, the behavior of the big block is predictable and easy to understand.
Think of it like this: imagine you have a big puzzle with lots of pieces that fit together. Sometimes, it's really hard to put the puzzle together because the pieces are all different shapes and sizes. But sometimes, the puzzle is easy and all the pieces fit together perfectly. That's what quantum triviality is like - when all the particles in the big block fit together in a simple and predictable way.