In today's lecture J.B was talking about how people use their own language when talking about a subject matter which seems to give them a sense of authority. In other words "Look I know the terminolgy about this subject which means I know what I am talking about and you don't, which means I know best" or something to that extent.
But in actual fact, us designers, whilst it is good for us to have all this terminology when communicating with likewise designers. Its not a good way with communicating with clients as they do not share the same knowlegde of the subject and see designs in a different way from us.
So when handling a client it is better to talk "their" language in terms of design from their point of view, rather than our own.