The phrase "selector lever" refers to a part in a vehicle that allows the driver to choose between different gears, like drive, reverse, park, or neutral. It's usually a lever that you move to change the gear of the vehicle. Full definition
The new M Sports Automatic is controlled by an electronic gear selector lever on the centre console and offers the driver not only the D Mode, but also an S and M Mode for an even more sporting gearshift. (ausmotive.com)
It is controlled using the short gear selector lever on the center tunnel and two paddles on the steering wheel. (ausmotive.com)
They can choose between the transmission selector lever of the touch control or (in a manner similar to Formula 1 vehicles) two shifting buttons on the ergonomic AMG sport steering wheel. (motor-prime.com)