Breathability means comfort. It allows moisture evaporation, so that when you're moving around your skin can breath. This keeps you dry and warm.
WINDPROOFING / WATER REPELLENCY
The material of the outer-shell is finely woven to repel water and wind. It's woven in such a way so as to allow breathability whilst keeping you dry.
Coating or Lamination
In addition to the material of the outer-shell, Authentech jackets have a coating or lamination which increased the waterproofing. Rain drops bounce off and don't soak in.
One of the primary reasons to wear a jacket is to stay warm. Through having quality insulation Authentech jackets stops heat leaving your body, whilst still allowing it to breath.