You have sent off for John, and he has given evidence to the obvious.
Jhn 5:33 Ye sent unto John, and he bare witness unto the truth.
Interesting and Hidden Aspects:
The Greek word translated as "sent" is apostello, and it is used to mean sending out messengers and messages. Our word "apostle" comes from this word. In addressing the mystery of witness suggested in the previous verse, Christ starts with the authority did they turn to for an answer. The answer is, of course, John the Baptist.
John, of course, gave his testimony or evidence regarding Christ. The word used to describe this evidence is translated as "the truth." The word is a noun, as opposed to the adjective translated as "true" in the previous verse.
As we said earlier, the Greek word means literally "unconcealed." We might say "exposed" or, in a more Biblical tone, "revealed." Another, perhaps more direct way of translating this idea is calling it "the obvious."
There is a bit of a joke here, because Christ is discussing a mystery here but in doing so, in this verse and the last, he keeps talking about what is obvious and easy to see.
πρὸς "Unto" is from pros (pros), which means "from (place)", "on the side of", "toward", "before", "in the presence of", "in the eyes of", "before (supplication)", "proceeding from (for effects)", "dependent on", "derivable from", "agreeable,""becoming", "like", "at the point of", "in addition to", "against," and "before."
Ἰωάνηνn "John" is from Ioannes, which is John in Greek.
καὶ "And" is from kai, which is the conjunction joining phrases and clauses, "and," or "but." After words implying sameness, "as" (the same opinion as you). Used in series, joins positive with negative "Not only...but also." Also used to give emphasis, "even", "also," and "just."
μεμαρτύρηκε (3rd sg perf ind act) Bear witness" is from martyreo, which means "to bear witness", "to give evidence", "give a good report", "testify to," and "acknowledge the value of." It is the basis for our word "martyr."