Meaning: Covering your mouth when you cough or sneeze is a polite way to prevent the spread of germs and keep others healthy.
Choice of Words: "Cover" means to put something over something else to protect or hide it. "Mouth" is the opening in the face through which people and animals eat, drink, and speak. "Cough" and "sneeze" are both sudden, noisy expulsions of air from the mouth and nose, often caused by irritation or a cold.