Plain English Meaning
The way the aircraft is set up for landing — flaps out, gear down, slower speed. It's how the airplane looks and behaves when it's getting ready to touch down.
Full Definition
The arrangement of an aircraft's flaps, landing gear, and other configurable surfaces or systems set for the approach and landing phase of flight. This typically means flaps extended (often fully), landing gear down, and power reduced, producing a higher angle of attack and lower airspeed than in cruise.
Context Anchor
Seen in stall training when a pilot practices how the aircraft behaves near a while set up as it would be during or landing.