the wicked and terrifying person

This does not refer to a specific person. It is a general statement. (See: rc://en/ta/man/jit/figs-genericnoun)

spread out like a green tree in its native soil

Here the prosperity of the wicked man is spoken of as if he were a healthy tree growing in good soil. (See: rc://en/ta/man/jit/figs-simile)