The word operation has several related meanings:

1. A planned activity or mission, especially one involving many people working together toward a goal. A military operation might involve troops, equipment, and careful coordination. A rescue operation brings together firefighters, police, and medical teams. When astronauts describe a successful operation, they mean everything went according to plan.
2. A medical procedure where a surgeon treats disease or injury. When someone needs an operation to fix a broken bone or remove an infected appendix, doctors work carefully inside the body to solve the problem. The patient is usually asleep during the operation so they don't feel pain. You might hear someone say they're recovering from an operation, meaning they're healing after surgery.
3. The way something works or functions. A factory's operations include all the processes that turn raw materials into finished products. When we talk about the operation of a machine, we mean how it runs and what makes it work.
4. In mathematics, a process that follows specific rules to get a result. Addition, subtraction, multiplication, and division are the basic operations you learn in elementary school. When your teacher asks you to perform an operation on two numbers, they want you to apply one of these mathematical rules.