Business communication is defined by Wikipedia as “communication that promotes a product, service or organization; relays information within a business; or functions as an official statement from a company”. Topics communicated usually include marketing; brand management; customer relations; consumer relations and public relations. In each one of the above you are representing your company so you need to handle yourself in a professional manner.
When you have to go speak on behalf of your company you need to determine what you are trying to communicate and to whom. Sometimes you have to communicate with your co workers and at other times with clients. If you need to show a presentation to one of your clients face to face, PowerPoint will always work best but you need to be able to communicate to present your presentation. You cannot prepare for this too much, and you need to be simple and to the point.