This question assesses how seriously you take your career aspirations and whether you are a determined, career-minded professional. The road to growth is never-ending. So they're interested in recruiting students who proactively improve their skills and knowledge. They're less interested in admitting students into their university who see graduating from college as the end-all-be-all of their goals.
They state in their student handbook, "Competent graduates will continually refine and revise their knowledge base to ensure they remain abreast of current scientific evidence and best practices in patient care. Demonstrating the ability to continually assess one's level of medical knowledge and constantly strive to augment it is essential for lifelong learning and delivering quality, patient-centered care."

Having a self-development plan is incredibly important for anyone. The interviewers want to know how attending Touro University will benefit your growth. As with any educational institution, it is in their best interest to invest their time and energy in the development and success of their future alumni. But they want to ensure their efforts aren't in vain, so they need assurances you'll put an equal or greater investment in yourself. If they are going to invest in you, they need to know that you have a plan in place for investing in yourself.