I do not understand

class Tower{
    let position: Point
    var range: Int = 1
    var strength: Int = 1

    init(x: Int, y: Int){
        self.position = Point(x: x, y: y)
    }
}

func fireAtEnemy(enemy: Enemy) {
        if inRange(self.position, range: self.range, target: enemy.position) {
            while enemy.life > 0 {
                enemy.decreaseHealth(self.strength)
                print("Enemy vanquished!")

            }
        }else {
            print("Darn! Enemy out of range!")
    }
    }

    func inRange(position: Point, range: Int, target: Point) -> Bool {
        let availablePositions = position.surroundingPoints(withRange: range)
        for point in availablePositions {
            if (point.x == target.x) && (point.y == target.y) {
                return true
            }
        }
        return false
    }