Possible meanings are 1) this is a metaphor representing Yahweh giving Jeremiah special authority to speak. AT: "Then it was as though Yahweh touched my mouth" or 2) Jeremiah was seeing a vision and Yahweh actually did this as a symbolic act of giving Jeremiah authority to speak. AT: "Then Yahweh touched my mouth with his hand" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/translate-symaction]])
This phrase represents giving Jeremiah his message. AT: "I have given you my message for you to speak to the people" or "I have enabled you to tell the people my message" (See: [[rc://en/ta/man/translate/figs-metaphor]])