It's a prayer that honors the Virgin Mary and seeks her intercession. The specific timing of when it is prayed may range dependant upon personal or community procedures. The hymn is sung (using the English translation "Hail, Holy Queen enthroned above") by a choir of nuns during the 1992 comedy https://encapsuladosvip.com/vita-pro-nobis-descubra-os-beneficios-dessa-incrivel-planta-medicinal/