How do I turn on the 'lighting' in the game

When I go to the detail setting, I see 'lighting' as off, and I can't do anything about it. I can change brightness level and other settings, but lighting.

Is there reason why, lighting setting is there, when I can't have a full grip of it?

Thanks in advance!

If the color is kinda grey and you cannot use this function that usually means that your video/graphic card is not supporting lighting. Maybe you should post which card you use so someone could tell you if it works with lighting or not.