Copper sulfate solution is aqueous (mixed with water), after some time the water will evaporate out leaving only the blue copper sulfate crystals in solid form.
When copper sulfate is added to water in a proportion a solution of copper sulfate is formed. If we add more copper sulfate to this solution and it is dissolved then this solution is called unsaturated solution. If we place unsaturated solution as it is nothing will happen to it. If you continue adding more solute until it does not dissolve more copper sulfate then this solution is called saturated solution. If we increase the temperature of this solution, then its ability to dissolve more solute is enhanced. When more solute is added to it, it will dissolve more solute until it becomes again saturated. This solution is called super saturated solution. If this solution is placed for sometime, water evaporates and we get crystals.