Nowadays, markets evolve faster than they used to do. The cause for this quick evolution of a specific market could be due to new technology getting cheaper or a macro change in human behavior. Investors are highly interested in investing in these evolving markets because the faster your market is changing, the bigger the opportunity is to multiply one's investment.
With the opportunity slide, you answer the question of why now is a great time to start your company and address a specific market. To awake the investor's interest, you have to give evidence why the market is changing and why now is the right time to invest in your company (e.g., substantial growth rates, confusion in the market, new regulations, low-cost technology,...).
After you have given all your information to your potential investor, he/she has to think: "He knows the market, and I agree with him that now is a great time to start this company." If you achieve that they will be more open to particular problems and your solution to it.
Famous Examples for new market opportunities are Netflix (high-speed internet made streaming services possible) or Mobile Apps (App Store created a whole new business section possible).
