How the sail boat works?

Answer 1

Wind pushes in to the sail on a sail boat, the boat then moves.

answer 2

It pushes only when sailing with the wind directly behind. Most of the time the sail is just like a wing, the curve of the sail causes the wind to move faster across the front of the sail (Bernoulli says faster air, less pressure), slower air behind sail (more pressure) sail generates "lift" in a horizontal direction and moves the boat. Controlling the shape of the sail and its orientation to the wind controls the lift it generates.

The keel counter balances the weight of the sails and rigging and the "lift" generated by the sails, it also keeps the boat from just skidding sideways across the water.