Plain English Meaning

It's the traditional round dial with a needle that shows how fast the aircraft is moving through the air. The needle swings around the dial as airspeed changes, the same way a car speedometer needle moves.

Full Definition

An analog airspeed indicator is a mechanical cockpit instrument that displays the aircraft's indicated airspeed using a moving needle on a circular dial. It works by comparing ram air pressure from the pitot tube with static air pressure from the static port, and converts the resulting pressure difference into needle movement across a calibrated scale, typically marked in knots.