Second line of defence in the middle. (Protects the Quarterback).
Line of scrimmage
He doesn't say soccer for a start he says football. And his dutys usually involve being the last line of defence between the atcking player and the keeper.
The line on which the ball is placed, before the snap, in American football is know as "The Line of Scrimmage"
The kicking teams 30 yard line.
45 yards ??
That's 40 yards
He ran 90 yards.