ἐκεῖνος ἐξηγήσατο: "he has made him known"

Says The verse opens with θεὸν οὐδεὶς ἑώρακεν πώποτε ("no one has ever seen God"). θεόν is fronted for emphasis, and ἑώρακεν is perfect. It closes with ἐκεῖνος ἐξηγήσατο. ἐκεῖνος is an emphatic resumptive pronoun ("that one") that points back to μονογενὴς θεός. ἐξηγήσατο (exēgēsato) is the aorist middle of ἐξηγέομαι (exēgeomai, "lead out; relate, explain, make known").

Usage: in the NT the verb has the standard glosses recount and report (Luke 24:35; Acts 10:8; 15:12, 14; 21:19). In wider Greek it is also used for interpreting sacred matters. Thayer s.v. ἐξηγέομαι (G1834) and BDAG s.v. are cited by reference only. The verb has no expressed object. "God" is understood from the opening clause.

Implies The verse is structured as a contrast. God is invisible even to Moses (cf. Exod 33:20, and 1:17 for Moses). The Son, who is himself God and is at the Father's side, has made the Father known. This frames the Gospel as that revelation (cf. 14:9).

Caution: English "exegesis" comes from this verb, but the English sense should not be read back into John. The point is revelation and declaration, not a technical method of interpretation.