What does Daniel 4:13 mean?

Thus were the visions of my head on my bed: I saw, and behold, a tree in the middle of the earth; and its height was great.

The tree grew, and was strong, and its height reached to the sky, and its sight to the end of all the earth.

The leaves of it were beautiful, and it had much fruit, and in it was food for all. The animals of the field had shade under it, and the birds of the sky lived in its branches, and all flesh was fed from it.

He cried aloud, and said thus, ‘Cut down the tree, and cut off its branches! Shake off its leaves, and scatter its fruit! Let the animals get away from under it, and the fowls from its branches.

Nevertheless leave the stump of its roots in the earth, even with a band of iron and brass, in the tender grass of the field; and let it be wet with the dew of the sky. Let his portion be with the animals in the grass of the earth.

Let his heart be changed from man’s, and let an animal’s heart be given to him. Then let seven times pass over him.