What is the penalty arc in soccer?

Answer 1

It is an arc that is drawn outside of the penalty area with a radius of ten yards and the center being the penalty mark. (Note: the mark is only 6 yards from the edge of the penalty area area)

Whenever a penalty kick is taken all players, except the kicker and the goal keeper, must be outside of the penalty area, at least ten yards from the mark, and not closer to the goal line than the mark.

Other than the taking of penalty kicks, it has no other function.