Vilfredo Pareto was an Italian economist. In 1906 he developed a theory that 80% of his country's wealth was owned by 20% of his country's citizens. Over time, this 80/20 principle / pattern has been noted to be true in other areas of life, and in particular, has been picked up by the business community. For example, it is said that 20% of your clients provide 80% of your income, 20% of your staff are responsible for 80% of your production, 20% of your time produces 80% of your results... There are many articles on Pareto's Principle, and once you are aware of it, it can help you to focus your time and resources more productively.
Below is a link to an article by Yaro Starak which expands on Pareto's Principle perfectly and explains how it applies today.
Personally, I'm a great believer that most of our creative thinking (80%!) is done in our subconscious mind, while we are away from the task. Often our best ideas come to us after or while exercising, dreaming, resting, meditating, playing, shopping, fishing or some other form of down time. These activities may also be called "procrastination" but in fact, time away from a task / business, is essential for renewing creativity and thinking up solutions to problems.
As with all new information, once you are aware of Pareto's Principle, you can take the parts which relate to you / your life / your business, and then use it to your own advantage.