First of all, make sure that you're using a version of the AirPods that supports wireless charging: either the 2nd Generation AirPods, or AirPods Pro.
Also remember that your AirPods still need to be in their charging case, and that the case needs to be placed on the wireless charging mat with the status light facing up.
The status light should illuminate for several seconds, then shut off while charging.
If the light never appears, you may need to fidget with the case's location on the pad.
If your case still won't charge, try using the Lightning to USB cable that came with your case instead.