The interviewer wants to be sure that this role, and the company, will meet your needs in the long term. If you are employed and looking for a new opportunity, the hiring authority will want to know how their job is different than the one you are looking to exit. Be honest about your current situation, but be careful not to overshare or speak negatively about your current position. It is best if you can focus primarily on your future wish list versus dwell on what is going wrong in your current job.