Okay, kiddo, let me tell you about something called variable refresh rate. Have you ever watched a video or played a game online and noticed that the picture looks a little bit choppy or jumpy sometimes? That's because most screens have a fixed refresh rate, which means that they refresh the picture on the screen a set number of times per second, usually either 60 or 120 times per second.
So if a video or game's frames (pictures that create motion in videos and games) don't match the refresh rate, then you might see some noticeable problems. But with variable refresh rate, the screen can adjust how quickly it refreshes the picture based on what's happening on the screen, so as to considerably decrease these problems. For instance, if the game or video has a lot of load to process, the screen will slow down the frames per second. When the video or game changes and becomes simpler, the screen will increase the rate of refreshing the picture.
It's like if your teacher was writing on the board and sometimes they wrote really fast and sometimes they wrote really slow. If you were trying to copy down what they wrote, it would be hard to keep up with them if they were going really fast or it would be boring if they were going too slow. But if the teacher wrote at a pace that matched how fast you were writing, then it would be a lot easier for you to keep up and understand what they're teaching you. That's kind of what variable refresh rate is doing for your screen.