WindowServer is a system process that is responsible for drawing and managing windows on the screen. It is started automatically when you login to your account.
If you are experiencing problems with WindowServer, such as slow performance or graphical glitches, you can try resetting the process. To do this, open the Activity Monitor application and find the WindowServer process. Select it and click the "Quit Process" button. You will be prompted to confirm, so click "Quit" again. This will force WindowServer to restart the next time you login to your account.