en_tn/zec/12/10.md

I will pour out a spirit of compassion and pleading on the house of David and the inhabitants of Jerusalem

Causing the people to be compassionate and to plead is spoken of as if the spirit were a liquid that Yahweh would pour on them. AT: "I will cause the house of David and inhabitants of Jerusalem to have mercy on others and to pray to me for mercy" (See: rc://en/ta/man/translate/figs-metaphor)

a spirit of compassion and pleading

Here this means to have a characteristic of compassion and pleading.

the house of David

Here "house" represents descendants. AT: "the descendants of David" (See: rc://en/ta/man/translate/figs-metonymy)

the one they have pierced

"the one whom they stabbed to death"

for an only son

It is understood that the "son" has died. AT: "for an only son who has died" (See: rc://en/ta/man/translate/figs-ellipsis)

the laments in Jerusalem will be like the laments at Hadad Rimmon

Hadad Rimmon may have been the place where the good King Josiah died of battle wounds after the Battle of Megiddo. It appears that the custom arose to hold periodic mourning there for his death. Some people, however, think that Hadad Rimmon was the name of a false god who was believed to die every year, an event for which his worshipers would go into mourning. (See: rc://en/ta/man/translate/translate-names and rc://en/ta/man/translate/figs-explicit)

Megiddo

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