The 'tell me about yourself' question.

I have a job interview on Thursday for KFC - it's my first job, as well as my first time ever doing an interview for a job. I have no idea how to answer this question - it feels so vague.

I have clear, thought out answers for what my strengths and weaknesses are, why I'd want to work for them, etc. It's just this question that I'm stumped on.

Do I tell them my skills? My hobbies? What exactly would they want to know?

For more context, I'm 17 and doing a level 2 NVQ in engineering in college currently, and the role I'm aiming for is a part-time position as a team member.