Metal + acid = salt + hydrogen
I’m guessing the reaction takes place in a solution of deionised water so the reactants form ions. 3 hydrochloric acid molecules dissociate into 3 protons and 3 chloride ions. The 3 chloride ions react with the 3+ charge on the aluminium ion, balancing the charges, forming aluminium chloride. 2 out of the 3 protons react to form hydrogen in its gaseous form. Dunno what happens to the 3rd proton. Maybe it’s reused, maybe it form a hydronium ion or maybe it just stays as it is. I dunno, man. I don’t even know if this is correct. What is life?