Eid al-Adha celebrates the time when Allah told the Prophet Ibrahim (Abraham) to sacrifice his son Ismail, both Ibrahim and Ismail accepted to do so and obey Allah. However, Allah stopped Ibrahim and gave him a lamb to sacrifice instead. On this day, every muslim that can afford to sacrifice a sheep does so. Muslims also give meat to poor people so they can also celebrate and enjoy Eid.
I wish you all a happy Eid!