Aerobic respiration needs oxygen in order to generate ATP. Oxygen acts as final acceptor in respiratory process. In pulse $e^{-}$(electrons) that energy from the electron transport chain ETC and take up protons from medium to form water.
It plays a vital role in respiration. $\mathrm{O}_2$ enters in the respiratory process at the end. It drives the process of aerobic respiration by removing hydrogen from the system. Thus, acting as final hydrogen acceptor.
By the process of oxidative phosphorylation the energy is produced, utilising the energy of oxidation reduction reactions.