They have to be at least 10 yards away or on their own goal line between the goal posts.
In a soccer game the wall is formed for a free kick.
When a free kick is awarded, not a penalty, and there is a chance the the player taking the kick could reach and score a goal, several players stand side by side between the ball and the goal. This forms the 'wall'.
three people stand together to make a wall on a free kick
In a penalty there is no defensive wall. In a free kick a goalkeeper puts 5-8 players in a line blocking the goal from the free kick taker, this limits the space in which the attacker can score in.
It's often called a wall.
If play is stopped to set this up, it is called a free kick. The players standing together is called a "wall."
On a penalty kick, the defensive "wall" is one person, the goalkeeper, who must be on the goal line between the goalposts until the ball is kicked. The penalty mark is 12 yards from the goal line, so the "wall" (goalkeeper) must be 12 yards from the ball. On a free kick (sometimes mistakenly called a "penalty kick outside the box"), all defensive players (including the "wall") must retreat to at least 10 yards from the ball. On an indirect free kick within the penalty area, the defenders may stand on the goal line between the goalposts even if it's less than 10 yards away (but it will always be at least 6 yards, because no attacking free kick is ever taken inside the goal box, which is 6 yards from the goal).
usually when it is a direct free-kick
a barrier made by footballers defending a free kick at goal
its when you kick your toe into a wall
learn how to slide tackle the ball before you hit the person. kick a ball against a wall and test your aiming with the soccer ball. If you call it soccer you should go play handegg instead.
The "wall" is designed to protect a large portion of the goal or goal area from the offensive strike. It should block the primary area the offensive player would like to place the ball. This allows the goalkeeper to defend the unprotected areas instead of the entire goal or goal box.