The Arrhenius theory of acids and bases states that…
Bases are substances that produce hydroxide ions in solution.
Acids are substances that produce hydrogen ions in solution.
The equation on the left shows an Arrhenius acid, hydrogen chloride produces a hydrogen cation in water. The equation on the right shows an Arrhenius base. Sodium hydroxide produce a hydroxide anion in solution.
https://upload.wikimedia.org/wikipedia/commons/thumb/9/92/Svante_Arrhenius_01.jpg/220px-Svante_Arrhenius_01.jpg