Multitudes. Note the Figure of speech Epizeuxis (App-6), to express "great multitudes".
decision. threshing: i.e. judgment. Compare Isaiah 41:15.
the day, &c. Defining the time as well as the place. Compare Joel 2:1.
Related Commentaries of Joel 3:14
Joel 3:14
14 Multitudes, multitudes in the valley of decision:d for the day of the LORD is near in the valley of decision.