What is a Cable operated disc brakes?

A disc brake is type of brake there a rotating disc (AKA rotor) is pinched between two brake pads mounted in a caliper to make the wheel stop turning.

There are two ways to make the brake pads pinch the rotor; hydraulic and mechanic/cable operated.

With mechanical/cable operated brakes the cable basically turns a screw which pushes one brake pad towards the other, pinching the rotor and slowing the bike down.