Your savoir-fair is your social smoothness. It will serve you well at parties, and on the first day at a new school.
As with so many French words that have English cousins, the French version somehow retains an edge of sophistication over its counterpart. The nearest English equivalent of savoir-faire is know-how. But while know-how pertains to nearly all skills, especially practical ones, savoir-faire usually refers specifically to skill in social and diplomatic situations.