Plain English Meaning

Turning the propeller blades back to their normal angle after they were stopped and aligned with the airflow, so the engine can run and pull the airplane again.

Full Definition

The act of rotating a feathered propeller's blades back from their streamlined, edge-into-the-wind position to a normal blade angle so the propeller can again produce thrust. On most light twins this is accomplished by repositioning the propeller control out of the feather detent, which allows engine oil (and on some installations a dedicated or spring) to drive the blades back to a angle suitable for restart and operation.