New light is any new teaching that the ORG thinks will keep them relevant as a "beacon" for the rank and file to follow. Funny, though, that some of the new light was actually old light that turned new again after the previous new light became old and then replaced by new.
Its like buying an LED light fixture to replace an incandescent only to use the LED for awhile then replacing it with the incandescent or maybe even a fluorsecent.
I have learned that the God of the Watchtower changes his mind a lot...