Everyone makes mistakes; no one is perfect. The interviewer knows that too and is asking this question to see how you handle situations when you make mistakes. Give an example that demonstrates how you took responsibility for your error and fixed it. Also, include what you learned from the experience as a result. Sometimes learning from our mistakes allows us to gain some valuable tools.

"When I first started my current job, I was a bit overwhelmed with the variety of drinks our customers ordered. One day, I mixed up three orders in a row. It wasn't because I didn't know how to make the drinks. It was because I wasn't actively listening, due to nerves. I made a Caf? Mocha instead of a Caf? au lait. Then, a Frappuccino instead of a Caramel Macchiato. I apologized profusely and quickly repaired the situation by making the correct drinks and offering to pay for the ones I made in error. Now, I am sure to actively listen to every customer as they place their specific orders."