The figure who served as a mentor doesn't necessarily need to be aligned to your profession of choice, although they certainly can be. This person could be someone who guided your work ethic, dedication, moral compass, or values. The goal here is to relay that they shaped the construct of your character in some manner. Keep it related to your professionalism or dedication. Any valuable lessons they imparted are worth mentioning here. Primarily, you'll want to convey how and why this person had an impact on you and how this impact guides and informs your character.