So many times we think of "fruit" as things we "do" for God - missions, evangelism, ministry, worship, etc but the truth is, Jesus was talking more about the "spiritual" fruit here of : love, joy, peace, patience , kindness, faithfulness, goodness, gentleness and self control. When we abide in Jesus and these things are evident and flowing through our lives it brings great glory to God. The evidence of the truth of Christ is clearly seen by those who are around us just by the way we live our "fruit-filled" lives.
Dwell in Me, and I will dwell in you. [Live in Me, and I will live in you.] Just as no branch can bear fruit of itself without abiding in (being vitally united to) the vine, neither can you bear fruit unless you abide in Me. I am the Vine; you are the branches. Whoever lives in Me and I in him bears much (abundant) fruit.
When you bear (produce) much fruit, My Father is honored and glorified, and you show and prove yourselves to be true followers of Mine.