Glory be to the Father, and to the Son, and to the Holy Spirit, as it was in the beginning, is now, and ever shall be, world without end. Amen.
The Glory Be is a very simple prayer, which is said at the end of each decade of the Rosary to bring a close to the particular Rosary Mystery being observed.
This prayer honors the individual three Persons in God: the Father, the Son, and the Holy Spirit. It is meant to be prayed with reflection for it deliberately emphasizes the name of each Person. Glory to God yes, but in particular to the Father, and to the Son, and to the Holy Spirit.
Furthermore, it gives the ultimate praise possible to the three Persons mentioned. This is indicated by the words: “as it was” clearly indicating that Glory is given without the conditions that come with time. In time, we have gradations, based on ordered events—this moment verses that moment. Rather, it is the Glory due to God in His Essence; it is never diminished, because there is never a time where God isn’t. He is out of time, having created time. He was in the beginning, is now and ever shall be. Thus all Glory is His.
“Father, the hour has come; glorify thy Son that the Son may glorify thee, since thou hast given him power over all flesh, to give eternal life to all whom thou hast given him. And this is eternal life, that they know thee the only true God, and Jesus Christ whom thou hast sent. I glorified thee on earth, having accomplished the work which thou gavest me to do; and now, Father, glorify thou me in thy own presence with the glory which I had with thee before the world was made.” (John 17: 1-5)
"O the depth of the riches and wisdom and knowledge of God! How unsearchable are His judgments and how inscrutable His ways! For who has known the mind of the Lord, or who has been His counselor? Or who has given a gift to Him that He might be repaid? For from Him and through Him and to Him are all things. To Him be glory for ever. Amen." (Romans 11: 32-36)