The result of a neutralisation reaction with equal amount of acid and base does not necessarily give a neutral solution, that is one with a pH of 7. And a solution of a salt is not necessarily neutral. This is because some cations and anions are acidic or basic in their own right.
Thus the product of the neutralisation reaction of hydrochloric acid and ammonia is ammonium chloride. But the ammonium ion is weakly acidic.
The result of this reaction is a solution of ammonium chloride, and this is slightly acidic because a very small fraction of ammonium ions react with water to give oxonium ions:
We say the ammonium ion is a weak acid. You will learn more about acids and bases in Section 14 on equilibria.