Shift lock is a special device that can be unlocked under certain circumstances. For example, when the vehicle can't start due to insufficient power, the vehicle can't be dragged in P gear at this time. At this time, you can press the shift lock button, the shift handle can be moved to the N gear, and the vehicle can be dragged. Generally, as long as it is automatic, this setting will be available.
The previous automatic transmission can switch from P gear to R gear, N gear or even D gear even when the engine is turned off, because there is no such function. However, in newer vehicles, because of the shift lock, it is impossible to shift gears when the engine is turned off, so to some extent, it can avoid the situation that the car slips when it accidentally shifts gears at rest.