en_tn_condensed/php/04/03.md

Yes, I ask you, my true companion

Here "you" refers to the "true fellow worker" and is singular. Paul does not say the name of the person. He calls him that to show he worked with Paul to spread the gospel.

along with Clement

Clement was a man who was a believer and worker in the church at Philippi.

whose names are in the Book of Life

"whose names God has written in the Book of Life"