The players

There are 15 players in a rugby team:

Number 1 and 3 are props.

Number 2 is the hooker.

Number 4 and 5 are lockers.

Number 6, 7 and 8 are flankers.

Number 9 is the scrum half. (when there are rucks , he does the passes, he also introduce the ball in the scrums)

Number 10 is the fly half. ( he's the main kicker )

Number 11 and 14 are wings.

Number 12 and 13 are centers.

Number 15 is full back.

Players from number 1 to 8 are called forwards: they take part in the scrum.

Players from number 9 to 15 are Backs.

I'll add a picture to illustrate my explanations.

Forwards are mostly very muscular, heavy and don't run very fast.

Backs are also muscular but less heavy and run way faster.