Answer: Potassium hydroxide, KOH, is considered a BASE in an acid-base reaction because it ACCEPTS a hydrogen ion from the other reactant.
According to Brønsted–Lowry acid–base theory, Base is a specie which accepts proton (H⁺) while, Acid is a specie which donate proton.
Bases may contain a negative charge or lone pair of electrons, while, Acids contain positive charge or a neutral atom with incomplete octet.
In given statement KOH is acting as a base because it contains a negatively charged hydroxyl group which can accept proton from a acid, i.e.
KOH → K⁺ + OH⁻
Reaction of OH⁻ with any acid,
K⁺ + OH⁻ + HCl → H₂O + KCl