Plain English Meaning

ATC has cleared you to fly down the runway low without telling you exactly how low. You pick the altitude, as long as you stay safe and at or below normal pattern height.

Full Definition

A low approach over a runway in which the pilot is authorized by ATC to fly down the runway at any altitude they choose at or below the published traffic pattern altitude, without being held to a specific minimum height above the surface. The pilot maintains responsibility for terrain and obstacle clearance and must remain within applicable airspace and noise rules.