When an acid solution is mixed with a basic solution, they neutralize each other forming

When an acid solution is mixed with a basic solution, they neutralize each other forming salt and water. 
A neutralization reaction occurs when an acid reacts with a base to form salt and water. Both the acid and the base cancel each other out in this reaction. Energy in the form of heat is released during this reaction. 

Example: Reaction of hydrochloric acid $\left(\mathit{HCl}\right)$ with sodium hydroxide $\left(\mathit{NaOH}\right)$: Hydrochloric acid reacts with sodium hydroxide to form sodium chloride $\left(\mathit{NaCl}\right)$ and water.

The reaction is:
$\mathit{NaOH}+\mathit{HCl}\to \mathit{NaCl}+H_{2}O$