A Linebacker is commonly referred to as an LB.
Yes, it is a football term
Linebackers are part of the defensive team, and line up approximately 3 to 5 yards (4 m) behind the line of scrimmage, behind the defensive linemen, and therefore "back up the line."
Uau, that info is very complex.
In football, the formation describes how the players on a team are properly positioned on the field.
That position is priceless for a team in order to have a good game.
Different formations can be used depending on whether a team wishes to play an attacking or defensive play.