Your interviewer is asking this question to hopefully get a couple of bits of information out of you. First, they'll be looking to hear that you have done your research on their company by reading a bit about them and recent happenings. Next, they'll be looking to hear that you have some personal investment into the organization that brought you to interview with them. Prior to your interview, try to research the company as much as possible so you have the ability to talk about one or two exciting things happening there that you can get on board with, if hired for this role. As you answer, try your best to speak with personal conviction.