Plain English Meaning
A quick way to figure out a safe speed for final approach: take the airplane's landing-configuration stall speed and multiply it by 1.3. That gives you a final approach speed with a comfortable cushion above the stall.
Full Definition
A rule of thumb for selecting a safe minimum approach speed in a single-engine airplane on a stabilized final approach in calm or near-calm wind. The recommended approach speed is approximately 1.3 times VSO, where VSO is the airplane's stalling speed in the landing configuration (full flaps, gear down, power off) at . Multiplying VSO by 1.3 yields a final approach speed that provides a safe margin above the stall while remaining slow enough for a landing. Manufacturer-published , when given, take precedence this rule of thumb.