If you have an Apple Watch, and your AirPods are paired to it, you can check the charge status of AirPods via the Watch's battery widget.
If the AirPods are literally all you have on you, then the only real way to check the charge is via the light inside the AirPods case:
If your AirPods are in your case, then the light shows the charge status of your AirPods. If not, the light shows the status of your case. Green means charged, and amber means less than one full charge remains.