When an interviewer asks what makes you unique, your answer should address one or more characteristic that makes you standout. This includes valuable abilities or qualities that make you perfect for the position. Interviewers really want to hear a compelling reason to hire new workers.
Begin preparation for this question by researching the job carefully. List qualities that are both unique and uniquely appropriate for the job, and then explain why these skills and traits make you a perfect candidate. If possible, give real-life examples of situations successfully resolved by applying those unique qualities. Keep it very short and to the point, offering no more than would fit on an index card. Be ready to answer the interviewer in a sincere and unrehearsed manner.