en_tn/2sa/01/12.md

for the people of Yahweh, and for the house of Israel

Both statements mean basically same thing. The word "house" is a metonym that represents the descendants of Israel. But, both "people" and "house" probably are a synecdoche representing the soldiers of Israel. Alternate translation: "for the Israelite soldiers" (See: rc://en/ta/man/translate/figs-parallelism and rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-synecdoche)

Yahweh

This is the name of God that he revealed to his people in the Old Testament. See the translationWord page about Yahweh concerning how to translate this.

they had fallen by the sword

Here "fallen" is a polite way of referring to being killed. Also, "sword" represents a battle. This here means "had been killed." Alternate translation: "they had died in battle" or "enemies had killed them in battle" (See: rc://en/ta/man/translate/figs-euphemism and rc://en/ta/man/translate/figs-metonymy)