Heaven and Earth are full of your glory
That's pleni sunt caeli et terra. The rest of the phrase is Gloria tua. So the whole phrase means, "The heavens and earth are full of your glory." pleni - full ; sunt - are; caeli - heavens; et - and; terra - earth; Gloria - glory; tua - your. It is part of the Santus that Catholics recite at Mass shortly before the Eucharistic prayer is begun. The language is, of course, Latin. The whole thing is: Sanctus, sanctus, sanctus, Domine Deus Sabaoth, pleni sunt caeli et terra Gloria tua. Hosanna in excelsis. Benedictus qui venit in nomine Domine. Hosanna in excelsis. Holy, holy, holy Lord God of hosts (armies), The heavens and earth are full of your glory Hosanna (praise) in the highest. Blessed is He who comes in the name of the Lord. Hosanna in the highest. Catholics put this hymn at that precise part of the Mass because they believe that when the priest says the words of consecration the Bread and Wine become the Body and Blood of Jesus Christ Our Lord and Savior. They are theerefore praising Him who is about to make Himself present on the altar.
I believe and I might be wrong that the original Shepherd song sung on the hilltop at Jesus Christ's birth was as follows but the song was probably first spoken in Aramaic which is the language which Jesus' people would have spoken at that time: In Latin: Sanctus, sanctus, sanctus Dominus deus sabaoth. Pleni sunt coeli et terra Gloria tua. Hosanna in excelsis. Benedictus qui venit in nomine Domini. Pleni sunt coeli et terra Gloria tua. Hosanna in excelsis. English translation: "Holy, Holy, Holy Lord God the power and might Heaven and earth are filled with your glory Hosanna in the highest. Blessed is he who comes in the name of the Lord Hosanna in the highest Hosanna in the highest Hosanna, Hosanna on high.
The Latin word "pleni" is pronounced as "PLEH-nee".
Taken in context together, "Sanctus" is the acclamation translated as "Holy" found at the opening of the Eucharistic prayer in Roman Catholic Church. "Sanctus"/"Holy" is a reference to the seraphic hymn of Isaiah (Is 6:3) which is also seen in the heavenly liturgy of Revelation (Rev. 4:8). "Benedictus" is the adjectieve "blessed", (Ps 118:26) in reference to those who "come in the name of the Lord". In classical music, these two elements "Sanctus" and "Benedictus" were sung during the consecration of "Traditional" Roman Catholic Mass, the Sanctus immediately prececeding, the Benedictus immediately afterwards. In the modern liturgy, the entire hymn is sung after the preface and before the Eucharistic prayer. The entire acclamation in English as found in the modern liturgy (ICEL): Holy, Holy, Holy Lord, God of power and might! Heaven and earth are full of your glory. Hosanna in the highest. Blessed is he who comes in the name of the Lord. hosanna in the highest. Latin: Sanctus, Sanctus, Sanctus. Domine Deus sabaoth. Pleni sunt coeli et terra et Gloria tua. Hosanna in excelsis. Benedictus qui venit in nomine domini. Hosanna in excelsis.