This is also the same question as 'Where do you want to be in 4 years?' The recruiter does not want to know about your personal goals i.e. you want a house in the south of France etc. They are only interested in your career ambitions.

Try not to sound too ambitious, for instance saying you want to have been promoted to the head of your department. This can scare off some interviewers who may think your after their job! Instead sound ambitious but realistic.

In four years time I aim to have improved my abilities and to be a leader in my field. This will mean that I can contribute more to my employers and their business.