What does Proverbs 21:23 mean?

Solomon lived in an era without the internet, recording devices, or mass communications. And yet, he still recognized the danger of uncontrolled speech. Some people talk too much, to their own detriment. The same Hebrew word is translated into English as "keep" and "guard." The person who guards his mouth and his tongue spares himself a lot of trouble. Lying, gossip, slander, and cursing have ruined many who would have stayed out of trouble if they had kept their mouths shut. In an era where every word can be recorded, broadcast, and criticized, Solomon's counsel is as appropriate today as when he gave it.

Of course, this advice is not easy to apply. The apostle James writes, "If anyone does not stumble in what he says, he is a perfect man" (James 3:2). He describes the tongue as a "a small member, yet it boasts of great things" (James 3:5), "a fire, a world of unrighteousness" (James 3:6), and "a restless evil" (James 3:8). He stresses how hard it is to control the tongue.