This question serves as both a test and an opportunity to provide any necessary clarification. The interviewers want to ensure that you have taken the time to thoroughly process the position description, and they also want to clear up any potential confusion or misunderstanding about the role prior to the start. Come prepared with a copy of the job description or a few key points written down. If you don't have anything that particularly surprises you, then you might share a component of the position that you are most looking forward to.