A business plan is simply a plan of what your goals are for the business, and how you plan to go about accomplishing them. Some people refer to it as a vision for your business. I like to refer to it as a blue print or a road map to accomplishing your goals. Your plan should be spelled out in clear and defining terms and be kept simple. It should be a written document and used as a tool in managing the business.
It could be, for example, the risk of a change in the economic environment _ what are your contingency plans for that in terms of dealing with such a situation? There may be many other risks as well specific to your particular sphere of operation, but that ability to plan ahead for all scenarios makes for a robust business plan. When I have received business plans, the very best responses come from people who have looked at the risks and have an answer for every question. What you never want is to throw a scenario at your plan and have to answer "I don't know what I would do in that situation". You want to plan for every possible contingency, and certainly all the major risks to the ongoing success of your business.