current core memory?

What is the current core clock of a video card (radeon)?
Also what is current memory clock?

 

In the CCC of my radeon, there are 2 places. One is for clock overdrive which shows core clock from 500 to 798 and memory clock from 500 to 988. Below, it shows the current values of 500 for core clock and 550 for memory clock.

I wonder what it means by current core clock? or current memory clock?