The divine keyword indicates that the power source of a class or power is the worship of a deity or adherence to a moral code.
Classes that draw power from the divine power source are:
Avengers, Clerics, paladins, and invokers have the Channel Divinity class feature, and can take a divinity feat to channel a deity specific power. Divine powers are also called prayers.
The other power sources are martial, arcane, primal, psionic, and shadow.