The author identified himself as “the elder”
"The elder unto the elect lady and her children, whom I love in the
truth; and not I only, but also all they that have known the truth;" (2 John 1:1)
Since the epistle addresses a group of people, many commentators conclude that “the elect lady” actually refers to a Christian congregation, which is evidenced by the last verse of the same chapter:
"The children of thy elect sister greet thee. Amen." (2 John 1:13)
The Greek term for church is feminine, and it was common to personify the Church as a woman (see Ephesians 5:25–27, 32; Revelation 12:1–4, 17; 19:7–8). Another possibility is that “the elect lady and her children” were John’s wife and family.
Chapter 52: 1 John, 2 John, 3 John, and Jude. New Testament Student Manual, 2014