What does Revelation 21:14 mean?

The wall of the New Jerusalem has twelve foundations on which the names of the twelve apostles are inscribed. The inscriptions are appropriate, because the church is "built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone" (Ephesians 2:20). When Jesus arose from the grave, He commissioned His apostles to proclaim the gospel worldwide. Wherever the apostles went, they declared that Jesus died, arose from the dead, and is coming again. Churches sprang up mainly because the apostles were faithful to the commission Jesus had given them.

The fact that the New Jerusalem displays both the names of the twelve tribes of Israel (Revelation 21:12) and the names of the twelve apostles shows two things. First, God distinguishes between Israel and the church, and second, both Old Testament believers and New Testament believers occupy New Jerusalem. God's grace avails for all who believe on His Son as their Savior.

Most likely, the twelve names here correspond to the original twelve apostles as established after the ascension of Jesus: Peter, John, James, Andrew, Philip, Thomas, Bartholomew, Matthew, James son of Alpheus, Simon, Judas son of James and Matthias (Acts 1:12–14; 1:26).