en_tn/rom/12/03.md

by the grace that was given to me I say

Here "grace" refers to God's choosing Paul to be an apostle and leader of the church. You can make this explicit in your translation. You can also translate this in an active form. Alternate translation: "because God freely chose me to be an apostle, I can say" (See: rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/figs-activepassive)

Do not think more highly of themselves than they ought to think

"Do not think you are better than other people"

rather, think in a wise way

"instead, you should be wise in how you think about yourselves"

each according to the measure of faith that God has given you

Paul implies here that believers have different abilities that correspond to their faith in God. Alternate translation: "since God has given each of you different abilities because of your trust in him" (See: rc://en/ta/man/translate/figs-explicit)