en_tn_lite_do_not_use/jer/04/15.md

a voice is bringing news from Dan

Here "a voice" represents a messenger. Alternate translation: "a messenger comes and tells about what is happening in Dan" (See: rc://en/ta/man/jit/figs-synecdoche)

Dan

This probably refers to the region of Dan, which was west of Jerusalem.

from Dan ... mountains of Ephraim

By hearing that the enemies had gotten to Dan and Ephraim, people in Jerusalem would understand that the enemies were getting closer to them.