The words “his,” “He,” and “he” refer to God.
The word “us” refers to Paul, the Ephesian church, and all believers in Christ. AT: “God planned long ago to adopt us” (See: rc://en/ta/man/translate/figs-inclusive)
“God chose us ahead of time” or “God chose us long ago”
Here “adoption” refers to becoming part of God’s family. Here the word “sons” refers to males and females. AT: “to be adopted as his children” (See: rc://en/ta/man/translate/figs-gendernotations)
God brought believers into his family by the work of Jesus Christ.
“Freely given us” here is an idiom for “abundantly” or “without hesitation.” AT: “he has abundantly given to us by means of the One he loves. (See: rc://en/ta/man/translate/figs-metaphor).
“the One he loves, Jesus Christ” or “his Son, whom he loves”