It's a new technique allowing saving results of light occlusion and shadows in a new layer of texture.
Generating and utilizing light baked textures can be used to add top quality visualization for mobile viewers not capable of performing those calculations in real time.
Light baking also can be used with Desktop and VR viewers to provide great quality shadows and lighting without wasting precious CPU power on calculating them.
Generate once use many times
Once you perform light baking for the model, the results are saved, results are not affected by the texture being used on the object, so the user can change texture, and texture scale without the need to regenerate light baking maps.