Saint Joseph’s Day, March 19, the Feast of Saint Joseph is the principal feast day of Saint Joseph, husband of the Blessed Virgin Mary. He is the foster-father of Jesus Christ. It has the rank of a solemnity in the Roman Catholic Church. It is a feast or commemoration in the provinces of the Anglican Communion, and a feast or festival in the Lutheran Church. Saint Joseph’s Day is the Patronal Feast day for Poland as well as for Canada, persons named Joseph, Josephine, etc., for religious institutes, schools and parishes bearing his name, and for carpenters. It is also Father’s Day in some Catholic countries, mainly Spain, Portugal, and Italy. It is a holiday of obligation for Roman Catholics, unless the particular Episcopal Conference has waived the obligation.
March 19 always falls during Lent, and traditionally it is a day of abstinence. This explains the custom of Saint Joseph tables being covered with meatless dishes.
(Source and where to find more information: Wikipedia)