A ten-code is like a secret language that police officers and other emergency workers use to communicate with each other on radios. It helps them talk quickly and without confusion, especially in stressful situations. Each code is a number combination, like "10-4" which means "message received" or "affirmative." Other codes can mean different things, like "10-20" which means "location" or "where are you?" It's important for emergency workers to learn these codes so they can talk to each other easily and get help to people who need it quickly.