@fed10-5
As you probably know the shape of waves, in a given place, is a mix of different kind of waves:

the windsea (produced by the local wind that you can observe locally) the main swell (produced by a strong wind far away) secondary swells (produced also by winds far away in other places).
All of them have different heights, come from different directions and show different peak periodes.
Swell 1 is the main swell, swell 2 and 3 are secondary swells.