An interviewer will ask you this type of question, typically early in the interview, for several reasons. First, it helps them understand your perception of what this job requires. They also expect you to describe characteristics that you possess. The final reason is that it gives them the information they can explore through additional questions. The best way to be prepared for this question is to carefully review the job description before going to the interview and read your resume in detail, so you are familiar with the skills and experience you have described and provided to the interviewer. Your answer should contain the elements of both of these.