Here's why:

* Solvent: The water is the solvent, the substance that dissolves the other substance.

* Solute: Salt (NaCl) is the solute, the substance that is being dissolved.

* Solution: The mixture of salt and water is the solution, a homogeneous mixture where the salt is evenly distributed throughout the water.

You can't see the individual salt particles in the water because they are dissolved at the molecular level.