The Brønsted-Lowry theory of acids and bases states that …
A base is a proton (hydrogen ion) acceptor.
An acid is a proton (hydrogen ion) donor.
In the reaction of HCl + H2O -> H3O+ + Cl-, HCl donates a proton and water accepts a proton fitting into the Bronsted-Lowry theory as shown in the image on the photos.
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Equilibria/Acid-Base_Equilibria/1._Theories_of_Acids_and_Bases