Sirach wanted his readers to listen to his instructions about their mouths. Do not get caught up by saying something you might regret. It is usually the words that you utter from your mouth that causes problems for sinners, revilers, and the arrogant.
Sirach reminds us that we should have self control. You should not follow your base desires, because you should restrain your various appetites. Do not let your soul take pleasure in these base desires. Otherwise, you will be the laughing stock of your enemies. Do not get caught up in luxuries. You might be impoverished by this attempt to enjoy luxury. Do not become a beggar by feasting on borrowed money, when you have nothing. Try a little self control.