Here "place my word in your mouth" represents causing Jeremiah to speak God's message. AT: "I will cause you to speak my message" (See: [[rc://en/ta/man/translate/figs-metaphor]])
"For my message will consume them." Yahweh's message was about how he would punish his people, so he speaks as if his message would destroy them as a fire destroys wood. AT: "For when you speak my message, it will destroy the people of Israel as fire destroys wood" (See: [[rc://en/ta/man/translate/figs-metaphor]])