The unknown solid acid in water can release its proton as this:
HA + H₂O → H₃O⁺ + A⁻
As we have the anion A⁻, when it bonded to the cation K⁺, salt can be generated, so the reaction of HA and KOH must be a neutralization one, where you form water and a salt
HA + KOH → KA + H₂O
It is a neutralization reaction because H⁺ from the acid and OH⁻ from the base can be neutralized as water
