The interviewer wouId like to know if you plan on staying with their company long term. If you have a history of jumping from job to job, this is a fundamental question to master. Show the hiring manager that you are capable of committing long-term and tell them why you feel their company will be "the one" for years to come.
"I do see myself growing my career here. I would like to be supervising or managing a team of my own in the next few years. I feel like I could progress here at a rate that will make this a possibility."
"I would love to see myself growing into a more prominent leadership role within your organization. My career interests align very nicely with your company's goals which helps me to see a great long-term fit here."