# they will say together with all the other nations ... mean?

This can be translated as an indirect quotation. Alternate translation: "they will ask with all the other nations why Yahweh has done this to the land, and what the heat of this great anger means." (See: [[rc://en/ta/man/jit/figs-quotations]])

# they will say together with all the other nations

"your descendants and the people of all the other nations will say"

# What does the heat of this great anger mean?

The writer is communicating one idea through two words. Alternate translation: "What does this terrible anger mean?" (See: [[rc://en/ta/man/jit/figs-hendiadys]])