Unfair advantage is something that you already have acquired or given. Identifying it can help you be successful with less effort. The best part about it is that everyone has at least one. The book categorizes them into 4 types, this is the MILES framework:
Money, Intelligence, Location, Education and Status.

Money: Not having to worry about finances is an obvious unfair advantage. Surprisingly in the book, authors highlighted how not having enough money can lead to an individual being more creative, which can be an unfair advantage too.

Intelligence: Having a sound intelligence can help in specific fields, like academic research, medical and tech jobs.

Location: When opening a business the location clearly matters. Moreover, which area you are living in also matters. If you were born in a humble village in Africa, the opportunities you will have will not be the same compared to someone who is residing in New York.

Education: Students from IITs or MIT will have an unfair advantage in placements. Also, it gives them a network of highly capable individuals. Having ample knowledge and experience in a field is also an unfair advantage.

Status: Having some following. If Elon Musk starts a new company tomorrow, everyone will have a positive outlook towards it or at least would hear its name.

After knowing your unfair advantages and strengths, try to improve them further. Choose a career which takes benefit from it. Try to improve your weaknesses in your personal life instead of professional. Determine the path of least resistance.

Information regarding MILES Framework and Reality Mindset was obtained from the book:
The Unfair Advantage: How You Already Have What It Takes to Succeed.

For more in-depth knowledge and more such lessons consider giving it a read.