Saturated steam is nothing but steam with dryness fraction 1 i.e. when heat is continuously supplied to liquid water it gets converted into a liquid-vapor mixture.
The moment at which the entire liquid is converted into steam is called dry saturated steam.
If this dry saturated steam is further heated only the temperature of the steam increases further. The more amount of heat we provide the higher its temperature goes.
This steam which is heated even after attaining a dryness fraction of 1 is called superheated steam.
From the figure below, the orange dot represents dry saturated steam with dryness fraction 1. The red dot represents the superheated steam. The dryness fraction has no meaning at this point.