God gave Jesus Christ a Revelation to show His servants the prophetic future.

He sent the Revelation of Jesus Christ in a series of visions to Saint John of Patmos to write down, which would form the Book of Revelation.  

"The Seven Golden Lampstands," refers to Churches of Asia who John sent these letters to, in the first three chapters of the Book of Revelation of the Holy Bible.  

Revelation 1:1-3  (NKJV)
Introduction and Benediction

1 The Revelation of Jesus Christ, which God gave Him to show His servants—things which must shortly take place. And He sent and signified it by His angel to His servant John, 2 who bore witness to the word of God, and to the testimony of Jesus Christ, to all things that he saw. 3 Blessed is he who reads and those who hear the words of this prophecy, and keep those things which are written in it; for the time is near.

Revelation 1:9-11(NKJV)
Vision of the Son of Man

9 I, John, both your brother and companion in the tribulation and kingdom and patience of Jesus Christ, was on the island that is called Patmos for the word of God and for the testimony of Jesus Christ. 10 I was in the Spirit on the Lord's Day, and I heard behind me a loud voice, as of a trumpet, 11 saying, "I am the Alpha and the Omega, the First and the Last," and, "What you see, write in a book and send it to the seven churches which are in Asia: to Ephesus, to Smyrna, to Pergamos, to Thyatira, to Sardis, to Philadelphia, and to Laodicea."

The Seven Golden Lampstands

Are the 7 main churches surrounding the area (Patmos) where Saint John of Patmos was exiled to by the Romans.  This is on the west coast of modern day Turkey facing Greece.

At that time, the Christians were facing increasing persecution. 

The Letters to the 7 Churches

God instructs Saint John of Patmos "John the Revelator," to write letters to the 7 main churches in that area. These 7 Letters comprise the initial chapters of the Book of Revelation, which is a book of Bible prophecy, The Revelation of Jesus Christ to John. 

God is giving each of these 7 churches "the 7 lampstands," specific instructions in these seven letters.

Jesus Christ placed a lot of importance on the Book of Revelation. It is the only book that He mentions a blessing for the reader who hears the words of this prophecy and keeps the instructions that are in it:

Revelation 1:3 (NKJV)

 3 Blessed is he who reads and those who hear the words of this prophecy, and keep those things which are written in it; for the time is near.

Application

These 7 letters can also be applied as instructions to modern day churches and individuals.  The letters to the churches contain instructions on a variety of topics, specific to each church.