This metaphor means that the punishment is about to start. This could be translated as "It is as if the ax has already been placed against the root of the trees" or "God is like a man who has placed his ax against the root of the trees." (See: [[rc://en/ta/man/translate/figs-metaphor]])
This is a passive clause. It can be translated with an active clause "He chops down every tree that does not produce good fruit." (See: [[rc://en/ta/man/translate/figs-activepassive]], [[rc://en/ta/man/translate/figs-metaphor]])
This can be translated with an active clause "throws it into the fire." (See: [[rc://en/ta/man/translate/figs-activepassive]], [[rc://en/ta/man/translate/figs-metaphor]])