This is similar to the question, 'what does it mean to make a great sale' You can change the words a little and use the answer for both questions. The key to this answer is explaining what it means to make a great sale, and then giving a good example of a great sale that you made.
This example has several key points. First, this answer is telling the interviewer what you believe is a great sale. Second, it is giving a good example. Finally, it is showing a good sign of an employee by saying, 'a person representing the company' All salesman or someone who works with customers is representing their company in some way. Saying this casually in an example is definitely powerful.