Plain English Meaning
The aileron and rudder controls are connected, so when you bank the airplane the rudder moves on its own to help keep the turn smooth. You don't have to push the rudder pedal yourself.
Full Definition
A flight control design in which the ailerons and rudder are mechanically or electronically linked so that movement of one automatically produces a coordinated movement of the other. When the pilot applies aileron to roll into a turn, the linked system applies the appropriate amount of rudder at the same time, helping keep the turn coordinated without separate rudder input.
Context Anchor
Seen in flight control system discussions, especially when learning how some airplanes reduce adverse yaw during turns.