RobH_en_tn/1ch/21/15.md

changed his mind about the harm

Here "mind" represents his decision. Alternate translation: "decided not to destroy Jerusalem" (See: rc://en/ta/man/translate/figs-metonymy)

Enough!

This exclamation means "You have killed enough people!" (See: rc://en/ta/man/translate/figs-exclamations)

draw back your hand

This is an idiom that means to stop doing something. Alternate translation: "do not kill attack the people of Jerusalem" (See: rc://en/ta/man/translate/figs-idiom)

Ornan

This is the name of a man. (See: rc://en/ta/man/translate/translate-names)