There is less mass per volume. The liquid water is more dense than the solid water - which is why ice cubes float on water. Units of density are, for example, grams per milliliter, pounds per cubic foot, kilograms per liter. Water is a great solvent. You can dissolve things into it.
Water is the solvent and sugar and flavoring are the solutes .
If you add too much solute, more than the solvent can dissolve, the solute will begin to fall out - the solution is saturated . The amount of solute in the solution is a measure of the concentration . A unit of concentration is, for example, grams of solute per liter of solvent. 10 grams sugar per 1 liter water. A solution made of an electrolyte will conduct electricity.