The text does not say who is being addressed, but it is clear that it is the people of Judah. Good News Translation and Die Bibel im heutigen Deutsch make this clear.

Him who is dead; that is, King Josiah. Both Die Bibel im heutigen Deutsch and Good News Translation spell out Josiah in their translations. Die Bibel im heutigen Deutsch has “People of Judah, do not weep for the king who has fallen; weep not because of Josiah!” Good News Translation says “People of Judah, do not weep for King Josiah….” Other translations identify the one who is dead in a footnote (New Jerusalem Bible, Traduction œcuménique de la Bible).

Bemoan means “mourn.”

The first two lines can be translated “People of Judah, don’t weep for the one who died, [King] Josiah. No, don’t mourn for him.”

Him who goes away; that is, Shallum (Joahaz) the son of Josiah (see verse 11). The meaning of the third line can be expressed by “But weep bitterly for the king who is exiled [or, carried away as a captive].” Most translations do not identify him by name, though Good News Translation does, and this can be helpful to readers who otherwise might not realize until verse 11 who he was.

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on Jeremiah. (UBS Helps for Translators). New York: UBS, 2003. For this and other handbooks for translators see here .