Basic Aim (=goal)

You win a rally if you hit the shuttle over the net and on the floor of the opposing side.
You lose the rally if you hit the shuttle into the net, or over the net but outside of the opposing side's court. You also lose the rally if, for example, the shuttle touches you or your clothing, or if you hit it before it crosses the net.

Serving

A shuttle on the line is "in". The receiver must stand still until the service is struck.

Scoring

You win a match if you win the best of three games. If the serving side wins a rally, it scores a point, and serves again but from the alternate service court. If the receiving side wins the rally, the score remains unchanged and the service passes to the next player in turn.
15 points wins a game.
Scoring in ladies' singles is slightly different. 11 points wins a game.

Vocabulary
a game : un set
a rally : un échange
to score : marquer
to serve : servir
the shuttle : le volant
to win : gagner
to lose : perdre
to hit : frapper
over : au-dessus
the net : le filet