What cancel out or neutralize acids?

A base, Alkali, Carbonate or metasl.

Here are the general equation's for acid neutralisation.

Acid + Base = Salt + Water

Acid + Alkali = Salt +Water

Acid + Metal = Salt + hydrogen

Acid + Carbonate = Salt + Water +Carbon dioxide.

Notice in each case, that the acid is converted to a (Chemical).SALT , which has a neutral pH of '7'.

NB An Alkali is a soluble base.