In general, SOLUBILITY is an ability of a substance to dissolve. In the process of dissolving, the substance which is being dissolved is called a solute and the substance in which the solute is dissolved is called a solvent. A mixture of solute and solvent is called a solution.
To put it in simple words:
When we insert sugar into water it will dissolve. In this process:
sugar is the solute
water is the solvent
One of the characteristics of table sugar is its solubility in water
That was a definition of solubility as it is used in a common language. Now let's see solubility as chemists understand it: