It suggests the brightness of the divine person and character.

Glory is associated with God's holiness.

(Isaiah 6:1-4) Our Lord Jesus is mentioned as the 'brightness of God's glory'.

He is also spoken of as being 'the express image of the Father', and we are told that he is at the right hand of the Father.

(Hebrews 1:3) The 144,000 members of his body are to be with him in his throne and in the Father's presence, thus in glory.