when an ocean wave hits the shore why can you feel it in your feet?

Waves are not just on the surface of the water. They run deep. They sort of roll while moving in toward the coast line. In fact, as they approach shallow water, the bottoms of the waves are slowed down by the friction forces while their tops roll on. And that's why we have breakers near the shore; the tops literally overrun the bottoms.

So those breaking tops fall down onto the shore and into the pilings that piers and restaurants sit on above the water. They hit these supports and the shore with considerable force at times. And that force is transmitted throughout the area...including "an ocean-side resturant [sic]" it seems.