Then the angel showed me the river of the water of life, as clear as crystal, flowing from the throne of God and of the Lamb down the middle of the great street of the city. On each side of the river stood the tree of life, bearing twelve crops of fruit, yielding its fruit every month. And the leaves of the tree are for the healing of the nations.
The tree of life is the same tree that Adam and Eve were prohibited from eating in the Garden of Eden. This tree is so large it spread on both sides of the river. Amazingly, it bears a crop of fruit every month. In the Heavenly Jerusalem, the tree offers fruit to those who believe and worship the One true God and His Son, Jesus the Messiah.
It appears that there is a time table of months in Heaven, but different than our earthly calendar. Second Peter tells us that one day is as a thousand years to the Lord (2 Peter 3:8).
The leaves of the tree are for the healing of the nations. The word ‘healing’ is the word ‘therapy’ or ‘therapeutic’ in English (1). What is implied here is that there will be treatment that promotes healing between peoples of different ethnicity not just in our own lifetime, but from the beginning of time. Each leaf contains something therapeutic that will help us to understand and appreciate each other, our decisions making processes, customs and lifestyles. How leaves will supply this remedy, I am not sure. But, someday we will participate and benefit from this wonderful service.
We are God's children and He desires for His family to be in unity and to respect and appreciate each other. Because of our Father's amazing love for us, even the leaves emanate life, bring healing, and promote pure love.
That’s what leaves mean in this verse.