A good way to tell if you understand your own business plan, product or service is whether you can describe it in the length of time an average elevator ride takes, aka the ‘elevator pitch’. Sometimes that’s all the time you’ll get to pitch it to the person making or breaking your future.
The smart people over at Knowledge Games have a great exercise to help you achieve that level of clarity and simplicity:

Often this is the hardest thing to do in developing a new idea. An elevator pitch should be short and compelling description of the problem you’re solving, who you solve it for, and one key benefit that distinguishes it from its competitors. It must be unique, believable and important. The better and bigger the idea, the harder the pitch is to write.

A great example of a company who understands this is The Future Well.
What is The Future Well and what do they do?
They provide a much needed service with an admirable focus, and they can tell you:

We identify either creative or disruptive business opportunities within the health space and design beautiful solutions that positively impact health and happiness.

And:

Sometimes we identify the opportunity and find the right partners to execute it and sometimes we build it ourselves. Other times, we help guide clients so the product/service is simple, elegant, and wrapped up with a business strategy that leverages their core competencies.