In the context of the verse, it could refer to the fact that the glory of the Word is the same as the glory of God the Father. Additionally, we have confirmation that the Son was sent by the Father (John 3:16; 1 John 4:14). Jesus is the unique and beloved Son of God, sent from God (John 3:16–17) to fully represent the Father on earth (John 14:9–10) and reveal the Father and his plan for salvation in a previously unparalleled way (John 3:16–17). The Son reflects the Father perfectly and perfectly carries out his will (John 5:17–18). The close relationship of Father and Son means their works and will are in perfect unity (John 5:19; John 10:30).
14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.