A surface which is hydrophobic is one which easily repels liquids. Inherently, glass is fairly hydrophobic–but it’s not perfect. In fact, the imperfections in glass cause liquids to still stick to the surface. A glass coating such as GlassParency will change this by ensuring a more hydrophobic surface.
When a surface is hydrophobic, liquids bead up on the surface and won’t alter the view. In fact, in some cases windshield wipers aren’t even necessary!