Highlighting' is the reflection of lights onto a surface.
With the new Material Wizard is that you can change all of these and quickly see the effect in the render preview window at the right.
This is the mirror like reflection of other objects
Highlight intensity or Sharpness
This controls "highlights" from the reflection of light sources. This is also sometimes called Glossiness.
Or Intensity-Y - this is how sharp or fuzzy the highlight is. Note how the Highlight Sharpness setting change the appearance of plastic. (The default Highlight Sharpness for plastic is 150.)
White, Metallic or colored - this determines the color of the highlight.