means The act of coming down to rest after flight or a fall, or the flat resting-place where a flight of stairs pauses or ends.

from From the verb "land," itself from Old English "land" — earth, ground, the solid stuff you eventually meet again. The "-ing" makes it the act of meeting that ground, whether you're a ship nosing toward shore, a plane easing onto a runway, or a foot finding the broad step that interrupts a staircase. That last sense — the stair landing — borrows the same idea: a small patch of level ground you arrive at mid-climb, a place to land before going on.