This is an idiom. Here "fall" represents destruction or failure. AT: "will be destroyed" or "awaits a bad future" (See: [[rc://en/ta/man/translate/figs-idiom]])
"Leaf" represents growth and prosperity. AT: "righteous people will prosper in the same way a healthy green leaf grows" (See: [[rc://en/ta/man/translate/figs-simile]])