So the Bronsted-Lowry definition of acid and bases states that an acid is a subtance that can donate a proton to another substance in a chemical reaction, while a base is a substance that can accept a proton from another substance in a chemical reaction.
It also states that the products that are formed from these acids and bases reacting are called conjugate acids and bases. Where a conjugate acid is define as an acid generated as a result of a base accepting a proton, while a conjugate base is defined as the base generated as a result of an acid donating a proton.
With this is in mind, what substances form when HCl dissociates in water?
Here is the reaction:
HCl + H2O ⇒ H3O+ + Cl-
The substances that form are H3O+ which is a conjugate acid and Cl- which is a conjugate base, all according to the definition of a Bronsted-Lowry acid and base.