In this passage, Jesus uses an object lesson for His followers. Remember this is the evening before His crucifixion. He’s been sharing with His disciples what matters most to Him.
Now Jesus and His disciples have left the Upper Room. Look at the last part of the last verse in ch. 14 (14:31). “Arise, let us go hence.” Apparently they are walking by torch light toward the garden of Gethsemane. Archaelogists tell us, there were vineyards outside the city walls. Jesus probably gestures toward or even picks up part of a vine.
In the OT, the vine was often used to refer to Israel. But they had been an unfruitful vine.
Look at v. 1: "I am the true vine, and my Father is the husbandman."
Jesus says, “You all know how Israel was supposed to be a vine that produced refreshing fruit. They failed. But I am the fulfillment of all that symbol suggests."
And then He tells us that we need to be growing and fruitful.