"son of a human being" or "son of humanity." God calls Ezekiel this to emphasize that Ezekiel is only a human being. God is eternal and powerful, but humans are not. See how you translated this in [Ezekiel 2:1](../02/01.md). AT: "mortal person" or "human"
God wants Ezekiel to speak to the mountains as if they were people. The message is for the people of Israel. (See: [[rc://en/ta/man/translate/figs-personification]])