It sounds like an easy question yet you have to ask them which part of you do they want you to describe.
Do they mean the business part of yourself?
Do they mean a particular part of yourself?
Do they mean on a regular basis or describe who you would be when/if you had to be in a particular situation?
You can't answer who you would be in a situation until you are faced with that situation.
The answer is complex because life happens and you have to adapt and change as you go to keep up with the never ending changes on your life's journey.
It's okay to simply say I am who I am.