You can find out every possible statistical parameter like chances of wave not occurring less than this more than that period so and so, what is the chance of a return cycle of a give wave; that means, after how many cycles statistically one particular height will repeat, what is the maximum height expected in 30 years, what is the maximum expected in 100 years. Everything can be found out form this formula, if you assume that to be a Rayleigh distribution in all statistical property becomes available, this is what we do.
Therefore, see things becomes simple from our point, if we can get an H s significant height and T p for a sea state for a given sea state I go to H s and T p, then I go to the I choose appropriate spectrum formula once I choose that I can find out every parameter what is the chance of you know a wave height exceeding so and so.