Plain English Meaning
The speed the company that built the airplane tells you to fly, written in the airplane's handbook. On final approach, it's the speed they've worked out as the right one for landing.
Full Definition
The airspeed specified by the airplane's manufacturer for a particular phase of flight or maneuver, published in the Pilot's Operating Handbook (POH) or Airplane Flight Manual (AFM). On final approach, it is the manufacturer's published target approach speed for the airplane in its current configuration and weight, intended to provide an appropriate margin above while keeping the airplane controllable in the .