Every person has different attitudes and approaches towards agile methodology. The employer tries to understand your point of view, and if it is the one they are looking for. Are you oriented on results of the project? Or do you care only for your paycheck? Also this can be found in you answer to this question.
The right answer really depends on your point of view. However, if you look for characteristics that are usually “positive” for the company, and you should do so, go with characteristics such as cross-functional team composition, face-to face communication, solving problems immediately after these are identified, working solution as a primary metric of progress, etc.
The most important thing is to look at it from the point of view of the employer and the project itself. Agile is popular not because it is thriving to use it in a project, but because it simply delivers the results. You can stress it in your answer, in order to convince the employer that you have the prosperity of his business on your mind all the time (even if it is not true :)).
Agile can be characterized by many ways. It is probably the most operational software development method, it is the one when the interaction in between the team members is the highest and typically it helps to shorten the product development cycle and avoid problems to occur once the team is finalizing, or testing the project.
But what I like the most about agile is the time efficiency. All the projects I worked on using agile methodology were completed in a given time frame and actually even earlier. The results were as expected, team members learned something from each other and at the end of the project, everyone was satisfied.