「Waves are formed from wind, the stronger the wind the bigger the waves"
When wind blows across the surface of water is produces small ripples, if the wind is strong and blows for long enough then these ripples get bigger and grow into lines of "swell". This swell then travels across the ocean and on impact with land of forms into a wave.
There are three main factors that determine the size and quality of a wave: The strength of the wind The wind duration, and The distance the swell has to travel before reaching land.