Doubt relating Installation instruction

At the end of page 25 of the user guide I found a Compatibility paragraph. In that I read about "3-plane light". What kind of light are they? Are they usable for FS9 scenery or only for FSX/P3D?

Moreover in the Installation paragraph I read:
If you plan to use AFLT with FS9 or FSX, copy the contentsof AFLT\Effects\FS9 or
AFLT\Effects\FSX_P3D, as applicable, from the archive into the applicable Flightsim
Effects folder.
If I plan to use BGL_Light instead of effects, do I need to copy the effects folder anyway or not?