At normal temperatures, sodium chloride (NaCl) dissolves in water at roughly 36 grams per liter.
Imagine you have a container with 100 grams of water. Add sodium chloride to the water and continue stirring until no more sodium chloride can be dissolved; roughly 36 grams of sodium chloride will dissolve in 100 grams of water. At this moment, the solution becomes saturated, which means that no more solute can dissolve in the solvent at the given temperature.