Ugh I always break out into hot sweats at this question. lmao!
Ok ... to try to be more helpful. IMO to answer this question well you do not have to answer this question incredibly precisely ... you just need to describe whatever direction you feel you are headed at whatever level of focus you can.
Whenever someone says they have no idea how to answer the question I think they are getting stuck because they do not know an exact answer ... and are not acknowledging what they do know ... which is often knowing what they do not want to do.
You have no idea of what you want to do ... really ... in 5 years you can see yourself on the road to being ... a doctor, an engineer, a poet, a beach bum, a priest, an actor, an American Idol contestant, a stay at home parent, a teacher, working for the geek squad, working on wall street, or volunteering in a 3rd world country? Every direction in life is still open? You have no areas of interest or areas you know of no interest? Really?
At 18 I was interested in Math, Engineering, Physics, Computer Science, or Architecture ... and I really had no idea where in that world I fit ... but I knew I wanted to leverage my analytical talents ... I just wanted to follow a path to figure how to use those skills. That was far from a precise answer but it was an answer that described my strengths and interest in general terms.