The giant in his haste forgot ’Twas Vinda’s hour, or heeded not. Those robbed at such a time obtain Their plundered store and wealth again. He, like a fish that takes the bait, In briefest time shall meet his fate.

In plain words: Jatayu explains that Ravana stole Sita at a special hour called Vinda, when anything stolen is always recovered by its owner. Like a fish that bites the bait, Ravana will soon meet his end.