They are asking you what you envision your practice being like one day. Do you want to be a private practice dermatologist? A leader in primary care? The head of an academic department? We can't tell you what your dreams are, only you can answer that.
Think of what medical practices do: serve a community, teach and train the next class of physicians, further medical knowledge via research..there are probably more that others can add. Then consider which of these you want your practice to fulfill, and to what extent, and then think of why you want those things.