Okay kiddo, I'm going to explain what "Chinese irredentism" means.
Imagine you have a toy that is broken into pieces and you really want to fix it and make it whole again. That's what Chinese irredentism is about but instead of a toy, it's about pieces of land that China used to have a long time ago.
So, a long time ago, China was a really big empire, but over time, parts of it were taken away by other countries. Chinese irredentism is a movement that wants to get all those lost territories back and make China whole again.
Some people in China argue that certain areas like Taiwan, Tibet, or parts of the South China Sea belong to China and should be brought back under Chinese control. These territories used to be part of China in the past, but now they are either independent or controlled by other countries.
Ultimately, Chinese irredentism is a political belief that promotes the idea that China should have all its territories back under its control. It is a controversial issue that has raised tensions between China and other countries in the past.