en_tn_condensed/rom/12/20.md

your enemy ... feed him ... give him a drink ... if you do this, you will heap

All forms of "you" and "your" are singular.

But "if your enemy is hungry ... his head."

"But the scripture also says, 'If your enemy is hungry ... his head.'" (See Proverbs 25:21)

feed him

"give him some food"

you will heap coals of fire on his head

Possible meanings are 1) "you will make the person who harmed you feel ashamed about how he has mistreated you" or 2) "you will give God a reason to judge your enemy more harshly"