Every computer, phone or tablet display has a refresh rate. Some displays are higher quality than others and refresh rate is one of the factors that determine the quality of a screen.
In Windows 11, you can see and even change the refresh rate of your screen. It could be a tablet display, laptop screen or even an external monitor on a desktop.
High refresh rate displays with 120Hz let you enable variable refresh rate. This basically means the refresh rate will vary depending on specific demands from applications and games. But you can obviously change it manualy.