Is medical saline a 0.9% solution of soda ash?

The concentration of saline is 0.9 percent to

0.9 percent saline is obviously not a concentrated solution.

The solubility of sodium chloride in water is much greater than this number

Saline means the concentration of sodium chloride in the body (0.9%),

What it means is: the concentration of the liquid environment in which the body's cells live!