1I saw, in the right hand of him who sat on the throne, a book written inside and outside, sealed shut with seven seals. 2I saw a mighty angel proclaiming with a loud voice, “Who is worthy to open the book, and to break its seals?” 3No one in heaven above, or on the earth, or under the earth, was able to open the book or to look in it. 4Then I wept much, because no one was found worthy to open the book or to look in it. 5One of the elders said to me, “Don’t weep. Behold, the Lion who is of the tribe of Judah, the Root of David, has overcome: he who opens the book and its seven seals.”
6I saw in the middle of the throne and of the four living creatures, and in the middle of the elders, a Lamb standing, as though it had been slain, having seven horns and seven eyes, which are the seven Spirits of God, sent out into all the earth. 7Then he came, and he took it out of the right hand of him who sat on the throne. 8Now when he had taken the book, the four living creatures and the twenty-four elders fell down before the Lamb, each one having a harp, and golden bowls full of incense, which are the prayers of the saints. 9They sang a new song, saying,
“You are worthy to take the book
and to open its seals,
for you were killed,
and bought us for God with your blood
out of every tribe, language, people, and nation,
10and made us kings and priests to our God;
and we will reign on the earth.”
11I looked, and I heard something like a voice of many angels around the throne, the living creatures, and the elders. The number of them was ten thousands of ten thousands, and thousands of thousands, 12saying with a loud voice, “Worthy is the Lamb who has been killed to receive the power, wealth, wisdom, strength, honor, glory, and blessing!”
13I heard every created thing which is in heaven, on the earth, under the earth, on the sea, and everything in them, saying, “To him who sits on the throne and to the Lamb be the blessing, the honor, the glory, and the dominion, forever and ever! Amen!”
14The four living creatures said, “Amen!” Then the elders fell down and worshiped.
The book of Revelation has enigmatic references to the "seven spirits of God"[1] in Revelation 1:4; 3:1; 4:5; and 5:6, and so it is difficult to know exactly what this identification means. Revelation 1:4 says that the seven spirits are before the throne of God. Revelation 3:1 indicates that Jesus Christ has the seven spirits of God. Revelation 4:5 identifies the seven spirits of God with seven burning lamps that are before the throne. Last, Revelation 5:6 connects to the seven spirits, who are "sent out into all the earth."
There seem to be three different ways that the phrase "seven spirits of God" may be interpreted from the most likely interpretation, in my opinion, to the least likely, but one cannot be dogmatic with the obscure expression. First, John may be referring to the usage in Isaiah 11:2 that says, "Yahweh’s Spirit will rest on him: the spirit of wisdom and understanding, the spirit of counsel and might, the spirit of knowledge and of the fear of Yahweh."
The seven references to the "spirit" may speak of attributes of God possessed by the Spirit of God, His identity with Yahweh, wisdom, understanding, counsel, power, knowledge, and fear of Yahweh.
The second option is that the "seven spirits" uses "seven," the number of completeness and perfection, to accentuate the Spirit of Yahweh's perfection.[2]
Last, of all, the "seven spirits" may refer to seven angelic beings, as is discussed in the book of Revelation (see Rev 4:6-9; 5:6-14; 19:4, 5), or to cherubim and seraphim.
[1] See the study of the "Spirit of God" in the Old Testament beginning at Genesis 1:2, and in the New Testament beginning at Matthew 1:18.
[2] For a discussion of the use of numbers in the Bible, see John J. Davis, Biblical Numerology - A Basic Study Of The Use Of Numbers In The Bible.