These may be the verses you’re talking about:
(Joh 14:28) You heard me tell you, ‘I am going away and I will come back to you.’ If you loved me, you would rejoice that I am going to the Father; for the Father is greater than I.
(Joh 14:29) And now I have told you this before it happens, so that when it happens you may believe.
(Joh 14:30) I will no longer speak much with you, for the ruler of the world is coming. He has no power over me,
(Joh 14:31) but the world must know that I love the Father and that I do just as the Father has commanded me. Get up, let us go.
I don’t know what point the speaker was making, I’d just advise being careful because this does not mean that the evil one is in control of the world or that God is not. The enemy is real and is around, but he can only influence a person to the degree that they allow him to, because Jesus has already conquered him.
The enemy being the prince of this age just means that a lot of people are serving him, knowing it or not, while in Heaven we’ll all be serving God alone.
(Joh 16:7) But I tell you the truth, it is better for you that I go. For if I do not go, the Advocate will not come to you. But if I go, I will send him to you.
(Joh 16:8) And when he comes he will convict the world in regard to sin and righteousness and condemnation:
(Joh 16:9) sin, because they do not believe in me;
(Joh 16:10) righteousness, because I am going to the Father and you will no longer see me;
(Joh 16:11) condemnation, because the ruler of this world has been condemned.