Answer to Question 1
A beach is an accumulation of sediment found along the landward margins of an ocean or a lake.
Answer to Question 2
When a wave approaches the shore, the water becomes shallower, and the wave begins to feel bottom at a water depth equal to its wave base. The slightly faster waves farther out to sea catch up, decreasing the wavelength. As the speed and length of the wave diminish, the wave steadily grows higher. Finally, a critical point is reached when the wave is too steep to support itself, and the wave front collapses, or breaks.