Suunto Kailash has two lights: a normal backlight and an extra bright backlight that you can use as a flashlight (see Flashlight).
To activate the backlight, keep the lower button pressed until the backlight turns on.
The backlight has three modes which can be changed in the options menu under GENERAL » Display » Backlight mode.
The backlight brightness level can also be adjusted in the options menu under GENERAL » Display» Backlight brightness.