In these verses, Nahum speaks of the people of Nineveh as if they were a group of lions, and of the city Nineveh as if it were their den. The metaphor speaks of the way in which the Assyrians would conquer other people and take their possessions as their own as if they were lions hunting prey and bringing the dead animals back to their den. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Nahum uses this rhetorical question to mock Nineveh, which has been destroyed. AT: "The lions' den is nowhere to be found ... afraid of nothing." or "Look at what has become of the lions' den ... afraid of nothing!" (See: [[rc://en/ta/man/translate/figs-rquestion]])