What does Ezekiel 3:12 mean?

I have made your forehead as a diamond, harder than flint. Don’t be afraid of them, neither be dismayed at their looks, though they are a rebellious house.”

Moreover he said to me, “Son of man, receive in your heart and hear with your ears all my words that I speak to you.

Go to them of the captivity, to the children of your people, and speak to them, and tell them, ‘Thus says the Lord Yahweh;’ whether they will hear, or whether they will refuse.

I heard the noise of the wings of the living creatures as they touched one another, and the noise of the wheels beside them, even the noise of a great rushing.

So the Spirit lifted me up, and took me away; and I went in bitterness, in the heat of my spirit; and Yahweh’s hand was strong on me.

Then I came to them of the captivity at Tel Aviv, that lived by the river Chebar, and to where they lived; and I sat there overwhelmed among them seven days.