Answer: It is a salt because it is formed by the reaction of an acid and a base.
Explanation: When an Acid and Base reacts with each other, the product formed is known as Salt. This reaction is a kind of neutralization reaction in which acid is being neutralized by the base.
Thus Sodium Chloride is a salt because it is formed by the neutralization reaction of the strong acid like HCl and strong base like NaOH