The gates will admit these leaders who will bring glory and honor to God from their respective groups of followers. This is a picture of worship in the new creation. [source][source][source]
". . . these verses reflect the ancient practice of kings and nations bringing their wealth and glory to the city of the greatest king. In the heavenly city, everyone will honor the "King of kings" (see Psalm 68:29; Psalm 72:10-11; Isaiah 60)." [1][source]
Context Summary
Revelation 21:9-27 - "the Holy City"
The "new Jerusalem" is the redeemed Church united with her Lord in the act of governing the whole world. A city is obviously the seat of imperial rule. In that blessed condition the saints will rule the earth as the powers of darkness rule it now. We shall enjoy the fellowship of the good and great of every age. In a literal sense we shall be fellow-citizens with the saints. All ages and dispensations will blend there. Angels at the gates; the names of the twelve tribes and twelve Apostles engraved in imperishable characters to indicate the blending of the dispensations; the differing stones, representing variety of character and function but all blending in the light of the Lamb on the throne.
The happy throngs pour through the gates with never-ending rapture. Those gates, facing every quarter, stand always open; but none desire to go forth, except commissioned on some errand by the King. All the glory and honor of the world are gathered within those walls, because Jesus will be king over every department of human life. There will be room for all beauty, art, and culture in the city of eternal light and love. [source]
Chapter Summary: Revelation 21
1A new heaven and a new earth 10The heavenly Jerusalem, with a full description thereof 23She needs no sun, the glory of God being her light 24The kings of the earth bring their riches unto her
Greek Commentary for Revelation 21:26
They shall bring [οισουσιν] Future active indicative of περω pherō Rome gathered the merchandise of the world (Revelation 18:11.). The City of God will have the best of all the nations (Isaiah 60:5,Isaiah 60:11), an expansion of Revelation 21:24. [source]
What do the individual words in Revelation 21:26 mean?
Andthey will bringthegloryhonorof thenationsintoit
Greek Commentary for Revelation 21:26
Future active indicative of περω pherō Rome gathered the merchandise of the world (Revelation 18:11.). The City of God will have the best of all the nations (Isaiah 60:5, Isaiah 60:11), an expansion of Revelation 21:24. [source]