HR is one of the job fields that offer a variety of career growth possibilities. This is true especially in big companies.
While people typically start as HR generalists, doing everything and nothing at the same time (few simple and repetitive tasks), they will (or should) aim for HR manager, or corporate recruiter, or payroll specialist position later (or other specialized HR role).
Before going to the interview, you should have a look at the website of the company and find out more about the hierarchy in their HR department. LinkedIn can help you if you are unable to find the information on the corporate website of the company. Identify some positions, and choose the one where you can see yourself in five years time.
Connect your future with the company
Recruitment is pretty expensive. Each company hopes to hire high quality employees who strive to stay with them for years to come, get a chance to be promoted, and embrace that opportunity. They do not want good people to leave them and work for one of their competitors. Therefore you should always connect your future to the company. Let me show you a good answer:
In five years time, I would love to have a position of a corporate interviewer, ideally a senior one. I know I have to learn a lot until this can happen. However, I believe I can learn the basics in your company, on a position of HR generalist (trainee).
No option for career growth
It may happen that you apply for a job in a small company, where HR department does not exist. In this case, there might be no room for career growth or promotion – a single HR position exists in the company–the one you try to get.
In such a case you should try to convince the interviewer that you do not look for career growth, and will be happy to have the same job in five years time.
I do not think about what I will do in five years time. One can be alive, but also dead, you never know. I just want to have a job in HR, and try my very best every day, to become a real asset for my employer. That would make me happy and proud.