''Nudba'' here means cry or wailing/lamentations. This is a dua of Imam Mahdi, and its recommended to recite this on the four eid days: Eid ulFitr (1st Shawwal), Eid al-Adha (10th of Dhu’l-hijjah), Eid al-Ghadir (18th of Du’l-hijjah), and Fridays.
آی-ویدئو