The length of time with no user action before the screen powers off.
Setting all sliders to the maximum value means 'Never'.
Note: this setting may be overruled by the Stay On action when the device is plugged into a power source.
Note: if you go to Android settings after running this action, Android will change the value to one it 'knows about' e.g. if you have set it to 9 minutes, Android Settings may change it to 10 minutes.
Some have reported the same thing occuring after a reboot.