Boots, played by Jude Mack, is the goalkeeper for Richmond's women's team in Ted Lasso season 4.
The goalkeeper is the player responsible for defending the goal and is the only position normally permitted to handle the ball inside the penalty area. In the show's new women's-team storyline, Boots is identified specifically as Richmond Women's goalie.
The character's nickname can make the role easy to overlook because “Boots” sounds more like a general football reference than a position. However, the official character listing identifies Boots as the team's goalie, which is another term for goalkeeper. That makes the answer distinct from the season's defenders and striker.