How do you explain information architecture to non designers?

I am working on a large financial application and would like to know few ways to present an IA or sitemap to other stakeholders (business development teams)

Do you start by explaining the goal or the problems with the current IA? or Should I just say - the homepage takes the user to point A,B,C then page A takes the user to sections A1,A2,A3. ?

Is there any better way to explain this?