Question Monitor is 144hz and 165hz overclocked. What does this mean?

[HerEyeSin]

I am getting pg279q ASUS monitor . Could someone explain please.

 

[velocityg4]

The hardware in it is a 144hz monitor. The manufacturer allows it to be pushed (overclocked) to 165hz. There may be no issues or graphical glitches when overclocked.