Jesus is referring to the spiritual life He gives to believers now while they are alive on earth. That life inside of us should bear Jesus fruit in our lives. The purpose of the vine is to bear fruit through its branches. Jesus chooses to bear fruit through His followers.

In John chapter 15:1, Jesus identified himself as the true vine. He is referring here to the central stalk rooted in the ground and provides support and nourishment to the branches attached to it. In John 15:5, Jesus identifies his disciples as the fruit-bearing branches.

The metaphor in John 15 is of a vine and its branches. The vine is the source and sustenance of life for the branches, and the branches must abide in the vine to live and bear fruit. Jesus, of course, is the vine, and the branches are people.