In Zechariah 2:4, this signifies the church of people who will receive the Divine proceeding of the Lord on a deep level within themselves. (Apocalypse Explained 629[6])

203. Verse 7. And to the angel of the church in Philadelphia write, signifies those of the church who are in the faith of charity. This is evident from the things written to the angel of this church understood in the internal sense, for (as was said above, n. 20) the "seven churches" mean, not seven churches, but all persons whatever who are of the church, or all things whatsoever with man that constitute the church; for "seven" in the Word means all persons and all things; for every number in the Word signifies something either of thing or state, as can be most plainly seen in this prophetic book, in which numbers are so frequently mentioned; and also in Ezekiel (chap. 40-48), where the new temple and the new earth are described, which is done by measurements given in numbers. The "new temple" and "new earth," here mean a new church, and each measurement or each number signifies something pertaining to the church. (That all numbers in the Word signify things and states, see in the work on Heaven and Hell 263.)