What is insoluble and soluble?

Soluble means when a solute that dissolves in a solvent it is known as soluble.

Eg: salt is soluble in water as it readily dissolves and mixes with water.

Insoluble means the solute is incapable of dissolving in the solvent. 

Eg: sand, fats, wood, metals, and plastic. When we put them in water and try to mix them, they will not dissolve.