Ensure that you have the latest version of macOS installed on your Mac. Then check whether Bluetooth is enabled on your device. Finally, go to System Settings → Bluetooth. You should see AirPods in the list of devices in this window.
Check whether the AirPods are charged.
If your AirPods don’t respond, you can restore them to factory settings. To do this, press and hold the button on the case for 3-5 seconds until the LED indicator blinks yellow three times.