In the Catholic Faith, holy days of obligation are days that require us to attend Mass. Sunday is described as the “primordial holy day of obligation,” according to the Code of Canon Law, hence we are expected to go to church on this day but there are other special days as well.
Saint Juan Diego is the patron saint of indigenous peoples. He is not just recognized as the first Roman Catholic indigenous saint from the Americas, he is well known for having seen an apparition of the Virgin Mary four times. We celebrate his feast day every year on December 9.