en_tn/jas/05/12.md

Above all

This is an idiom that can be translated as "This is important" or "Especially"

my brothers

"my fellow believers"

do not swear

to "swear" is to say that you will do it and to be held accountable by a higher authority. alternate translation: "do not make an oath" or "do not make a vow."

either by heaven nor by the earth -

The words "heaven" and "earth" are metonyms that refers to the powers that are in heaven and earth. See UDB. (See: rc://en/ta/man/translate/figs-metonymy)

your "Yes" mean "Yes" and your "No" mean "No"

This could be translated as "do what you say you will do without making an oath."

so you will not fall under judgment

"so God will not punish you"