en_tn/2co/12/02.md

I know a man in Christ

Paul is actually speaking of himself as if he were speaking of someone else, but this should be translated literally if possible.

whether in the body or out of the body, I do not know

Paul continues to describe himself as if this happened to another person. "I do not know if this man was in his physical body or in his spiritual body"

the third heaven

This refers to the dwelling place of God rather than the sky or outer space (the planets, stars, and the universe).