What does SHIFT mean when it appears on the car dashboard?

[VanFinn]

SHIFT: As a noun, it means change, movement, or shift; as an adjective, it means altered or transferred. At 15 mph, it prompts the driver to shift to 2nd gear; at 30 mph, to 3rd gear; at 45 mph, to 4th gear; and at 59 mph, to 5th gear. Here is some additional information: Automatic transmission shift-lock key: Most automatic transmission vehicles have a Shift-lock key, whose main function is to prevent the transmission from failing to move the gear. Pressing it can force the gear to move. Another function is in parking lots, where parking attendants sometimes require manual transmission cars not to engage the handbrake, and automatic transmission cars to not only disengage the handbrake but also place the gear in the N position. This allows parking attendants to move the vehicle when it obstructs the entry or exit of other cars.