What does Revelation 5:11 mean?

According to this verse, John heard the voice of many angels—too many to count. The Greek phrases used here are myriades myriadōn and chiliades chiliadōn. The first phrase uses the root word myrias, which is sometimes used to mean "many" or "multitudes," but is also used to mean a literal figure of 10,000. At least according to the words used, then, one "myriad of myriads" would be 100 million angels! However, the point doesn't seem to be giving an explicit number, but rather the massive scale of beings involved. Colossians 1:16 credits Jesus with the creation of all things, including the angels. The fact that an innumerable host of angels exist in heaven to serve God points to Jesus' omnipotence. It also points to the fact that heaven is far from empty.

Psalm 68:17 states, "The chariots of God are twice ten thousand, thousands upon thousands; the Lord is among them." The angelic host that John heard was celebrating the Lamb's reception of the sealed scroll from the One who was seated on the throne (Revelation 5:7). They were also celebrating the approaching reign of Jesus on the earth (Revelation 20:4–6). The impending establishment of Jesus' earthly kingdom caused them to rejoice greatly.

Although angels do not experience redemption, they are keenly interested in the phenomenon. First Peter 1:12 reveals that angels "long to look" into matters pertaining to our redemption.