DSG S sector on gate

I thought it stood for Snow until I read the handbook. I assume you have no handbook.
In 'S' (Sport) mode the gearchanges upwards are held until almost maximum revs. to maximise accceleration. Better still when preparing to overtake and are in normal D mode changing to S will change down a gear for you again so as to maximise acceleration. Clever stuff.
Stick to D for normal driving though if you care about MPG.