The text at her YouTube channel says, "Shakira, before the Pope at the UN in NYC, dedicates her performance of John Lennon's Imagine to Aylan and Galip Kurdi and all the children turned refugees due to the Syrian war / Shakira, frente al Papa en la ONU, dedica su actuación a los hermanos Aylan y Galip Kurdi y a los niños refugiados por la guerra."
I can't quite tell from the reports I've seen, but it seems as though the Pope may have left the Assembly hall before she sang. (Shakira le canta 'Imagine' al Papa en la ONU El Periódico 25.09.2015)
Also on Shakira's agenda was meeting with the attorneys of her former boyfriend Antonio de la Rúa to try to settle a lawsuit in which De la Rúa is demanding a portion of her earnings from the time they were together. (Shakira viaja a Nueva York para ver al Papa y arreglar cuentas con su ex El Espectador 24.09.2015)
I don't see Shakira in the following video herself, although she has very publicly expressed her solidarity with it. (Shakira, Santana, y Gloria Estefan cantarán contra Donald Trump El Espectador/EFE 24.09.2015)
It's a video made in solidarity with American immigrants and American-born Latinos against the racist, xenophobic, God-hating immigrant-bashing being practiced by Donald Trump and the supporters of his white-trash bigotry, Video musical "Todos Somos Mexicanos" Univision Noticias 09/21/2015: