What is the semi circul at the penalty box for?

The semi-circle at the penalty box, known as the "arc," is used to ensure that players maintain a proper distance during a penalty kick. When a penalty kick is taken, all players except the kicker and the goalkeeper must remain outside of this arc, specifically at least 10 yards away from the penalty spot. This rule helps to prevent crowding and interference, allowing the penalty taker a fair opportunity to score. The arc extends from the penalty box's outer edge to reinforce this distance requirement.