Sing and rejoice. The Jews released from Babylon, and the whole Jewish nation, are bidden to exult in the promised protection and presence of the Lord. Lo, I come; Septuagint, ἰδοὺ ἐγὼ ἔρχομαι, So Christ is called, ὁ ἐρχόμενος, "he that cometh" (Matthew 11:3).
I will dwell in the midst of thee (Zechariah 8:3; Zechariah 9:9). Not merely the rebuilding of the temple is siginified, and the re-establisihment of the ordained worship (though without the Shechinah), but rather the incarnation of Christ and his perpetual presence in the Church.
κατασκηνώσω ἐν μέσῳ σου, which recalls John 1:14, "The Word was made flesh, and dwelt ( ἐσκήνωσεν) among us" (comp. Isaiah 12:6; Ezekiel 43:9; Ezekiel 48:35; Malachi 3:1).