Looking at the mechanism used in this wooden bowling game, I guess it is played like this:
 Preparation:
 Place the small wooden pins in the middle of the game board in an upright position.
 There is a rope and a ball at the end of the curved bar on the side.
 Shot:
 Pull back on the ball at the end of the stick and release.
 When released, the ball makes a swinging motion, trying to hit the pins.
 Scoring:
 The more pins you can knock down, the higher your score will be.
 The player with the most points after a certain number of rounds wins.