Normally, your TV is designed to update the picture it displays a fixed number of times every second at a very regular interval. This is called a refresh rate.
60 hertz (refreshes per second) is the most common refresh rate, though most modern displays will also accept signals at 24hz for watching 24 FPS movies.
Your game console needs to adhere to this refresh rate and provide a new image at each regular interval. If your game is struggling to keep up with the refresh rate, then the console will deliver a second copy of the previous frame (resulting in stutter) or it will send over the partially complete current frame and fill in the rest with the previous one ( resulting in “screen tearing”), depending on how the game is programmed.
VRR stands for variable refresh rate. It allows the game console to push new frames to the TV as they become ready instead of only at the fixed interval. This eliminates the stutter and screen tearing caused by a slight mismatch in the game’s frame rate and the display’s refresh rate.