Executive Summary should address the following:
Provide a business description and clearly define what your business will be doing. (This is really explaining what your business is attempting to do).
List the founders and executive team, and provide their backgrounds and relevant experience. Also provide your immediate and long-term staffing needs. (Have some fun with this. What experience (cleaning room, etc.) do you have and what experience do people helping you have).
Explain your product, including customer needs and applications. (What is your product, do customers need or want your product and how will your customers use and enjoy your product).
Barriers to Entry.
How difficult is it to get your business started and for others to do the same thing as you are doing. Can you protect yourself from other people copying your name, signs, advertising etc. Can people do the same thing in the same area. (This is a difficult area to consider. In the lemonade stand business you may be able to get exclusive territorial rights for an area - your front lawn).
Explain how your business is different from others. What is so great about what you are doing. If people don't see value in it, if it doesn't help them they will not buy your product.
Describe the market opportunity, including the size, history, characteristics, and dynamics of the market, showing how you fit in the market. (How much do you think you can sell, to who and where).
Describe your competitors, their relative strengths and weaknesses.
Describe your marketing strategy and the proposed business model, including a discussion on sales and distribution channels. Provide details on what market validation (research) you have conducted and your current status with any customers. (How are you going to run your business, tell people about your product and business and why you have made these decisions).
State the amount of the investment you are looking to raise and your funding history. List your future milestones and the amount of capital required to reach these milestones. (How much money do you need, when will you need it and how well will your business do with the money you are given).