“He is the radiance of the glory of God and the exact imprint of his nature.” (Hebrews 1:3)
Jesus relates to God the way radiance relates to glory, or the way the rays of sunlight relate to the sun. Keep in mind that every analogy between God and natural things is imperfect and will distort if you press it. Nevertheless, consider for example, There is no time that the sun exists without the beams of radiance. They cannot be separated. The radiance is co-eternal with the glory. Christ is co-eternal with God the Father. The radiance is the glory radiating out. It is not essentially different from the glory. Christ is God standing forth as separate but not essentially different from the Father. Thus the radiance is eternally begotten, as it were, by the glory — not created or made. Like the rays of the sun are an extension of the sun. So Christ is eternally begotten of the Father, but not made or created. We see the sun by means of seeing the rays of the sun. So we see God the Father by seeing Jesus.
So I commend this great Person to you that you might trust in him and love him and worship him. He is alive and sitting at the right hand of God with all power and authority and will one day come in great glory. He has that exalted place because he is himself God the Son.