What does 2 John 1:13 mean?

This final verse of 2 John is a very brief signature. The "children" referred to are almost certainly the believers with John in his current location. We aren't sure if John is with a few Christian friends or an entire church, but he is clearly in touch with some type of Christian community. This is in contrast to the book of Revelation, which John wrote while alone in exile on Patmos (Revelation 1:9). In Revelation, John is alone and hearing directly from the Lord.

These fellow believers were spiritual family with the recipients of John's letter. Using terms such as "children" and "sister" implies relationship. John is using familial terms for believers in his location and those receiving his writing. These fellow Christians send greetings, which are simple positive blessings to those they could not visit in person at the time. Still today, believers often send greetings to one another while apart. Likewise, we long to see one another in person, view one another as family, and anticipate eternity together with Christ.

The reference to the "sister" in this verse is a strong reason to think that the "elect lady" mentioned earlier in this letter is an entire church or community, rather than a single person.