High from the briny deep upreared The monster’s hideous form appeared, “Sugríva’s tale,” he cried, “is true: This is the demon dire to view Of whom the Vánar monarch told, Whose grasp a passing shade can hold.”

In plain words: Hanuman sees the ugly monster rise out of the sea. He remembers that King Sugriva had warned him about a demon who catches creatures by grabbing their shadows.