It is implied that "do not understand" means they ignore or do not honor Yahweh's works. Alternate translation: "they do not regard with honor what Yahweh has done" (See: [[rc://en/ta/man/translate/figs-explicit]])
Here "hands" represents what Yahweh has done or created. Alternate translation: "what he has created" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The punishment of the wicked people is spoken of as if they were a building or a city that God would destroy. (See: [[rc://en/ta/man/translate/figs-metaphor]])