The phrase "left paddle" refers to the paddle or oar on the left side of a boat that is used for steering and moving the boat in a specific direction. Full definition
But the engine's torque is such that gear selection is almost secondary in normal driving, meaning most will leave the paddles well alone. (autoexpress.co.uk)
A separate «M» button leaves the paddle - shifters entirely in control of the gearbox. (slashgear.com)
The driver initiates shifts with either the console shift lever (tip forward for downshifts, rearward for upshifts) or «paddles» on the steering wheel (left paddle for downshifts, right for upshifts). (bmwusanews.com)