Waves data exact defintions

Just wondering if you can tell me exactly what the data for waves is actually showing. I believe you are saying that the waves height is the mean wave height, but is this for example the mean significant wave height (Hm0), or (H1/3)? Or is it simply the mean height of all waves in a period of time. And then what is the time period for calculating the mean? I understand what the wave period refers to but am not certain either about what the third value provided is indicating!