And a slinger is someone who has a leather pouch with two long cords attached to it, and they put a projectile, either a rock or a lead ball, inside the pouch, and they whirl it around like this and they let one of the cords go, and the effect is to send the projectile forward towards its target.
投石手というのは 革製のポーチを持っていて このポーチは ２本の長い紐付で 弾にする石や鉛玉を このポーチに入れ こんな風に回転させて 一方の紐を放す事で 標的に向けて 投擲するんです