Plain English Meaning
Pulling the flaps back up into the wing after they were lowered. This is done step by step once the airplane has enough speed to climb without them.
Full Definition
The process of moving the wing flaps from a deployed (extended) position back to a stowed (up) position, typically performed in stages after takeoff or during a go-around to reduce drag and allow the airplane to accelerate and climb more efficiently.
Context Anchor
Pilots encounter flap retraction during configuration changes after takeoff, after landing, and when abandoning a landing and climbing away.