what do u understand by the phrase "two tower of darkness"?

Kino and Juana are about to dispose of the pearl. This image of the "towers of darkness" symbolizes Kino and Juana’s situation. Some critics argue that their brightest days are behind them, and a dark patch of their own making lies ahead. Some critics argue that Kino's material obsession has come to an end and the "darkness" is behind them with the renunciation of the pear. I'd, go with the former because they are now broken people who have lost their true pearl; they have lost their child.