Water is an almost perfect solvent. Lots of stuff will dissolve - go into solution - in water. Each of those things will only dissolve in water up to where the water is saturated with that thing. But, water can be saturated with lots of things simultaneously. Gases, such as CO2 dissolve in water, and like sugar dissolved in water, you can't see the substance that is dissolved.
Man! Am I a Chemistry teacher or what??