Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come. He will guide you - He will consider your feeble infant state; and, as a father leads his child by the hand, so will the Holy Spirit lead and guide you.
The Vulgate, and some copies of the Itala, read, He will Teach you all truth; but this and more is implied in the word ὁδηγησει, he will lead; besides, this reading is not acknowledged by any Greek MS.
He shall not speak of himself - He shall teach nothing contrary to what I have taught you:
But whatsoever he shall hear - Of the Father and me, that he shall speak, and thus show the intimate consent between himself, the Father, and Christ. It is one conjoint testimony, in which the honor and glory of the holy Trinity, and man's salvation are equally concerned.
And he will show you things to came - He will fully explain every thing that may now appear dark or difficult to you; will give you such a knowledge of futurity as shall, in all necessary cases, enable you to foretell future events; and shall supply every requisite truth, in order to make the new covenant revelation complete and perfect.