I'm not a programmer, so I'm not the best person to break it down for you. There are plenty of articles on Medium and elsewhere that can explain it better than I can, but in short: ChatGPT doesn't "understand" you. That's not a thing. It simply predicts what should come next in the conversation based on predictive text, trained on a vast dataset. That's it. People are making ChatGPT out to be an "intelligent" sentience and it... isn't. At all.

How ChatGPT Works: https://towardsdatascience.com/how-chatgpt-works-the-models-behind-the-bot-1ce5fca96286

https://medium.com/@techynilesh/behind-the-bot-how-chatgpt-works-and-the-models-powering-its-natural-language-processing-623e7a284f9b