en_tn/php/01/03.md

I thank...I pray...I give thanks

Here "I" refers to Paul. (See: rc://en/ta/man/translate/figs-singularpronouns)

you

Here "you" refers to the Philippian believers. (See: rc://en/ta/man/translate/figs-you)

I give thanks for your fellowship in the gospel

Paul is expressing thanks to God that the Philippians are also preaching the gospel. AT: "I give thanks to God for you proclaiming the gospel"

I am confident

"I am sure"

he who began

"the God who began" or "God who began"

will complete it

"will continue to complete it"