en_tn/rom/01/03.md

concerning his Son

This refers to "the gospel of God," the good news that God promised to send his Son into the world.

Son

This is an important title for Jesus, the Son of God. (See: rc://en/ta/man/translate/guidelines-sonofgodprinciples)

who was a descendant of David according to the flesh

Here the word "flesh" refers to the physical body. Alternate translation: "who is a descendant of David according to the physical nature" or "who was born into the family of David" (See: rc://en/ta/man/translate/figs-explicit)