Depending on the layout you decide on for the cover for your print book, you may have a place to include a back cover bio. Even if you already have an About the Author section, you might want to include a shorter bio on your cover.
When someone looks at your book on Amazon, they will see both the front and back cover images. Having a back cover bio is another way to get potential readers interested in what you have to say.
The back cover bio should include why you are an expert on this subject and make you seem approachable, humor works well for that. It really should only a few sentences. The About the Author page will be more in depth.
You could include reviews or quotes from recognizable authorities on your back cover instead of an author bio if you like. The effect is the same. Reviews garner interest. Interest increases the likelihood of a purchase.
Both your About the Author bio and the back cover bio should also be included on your author website. The About the Author bio is your About page on your website. The back cover bio might appear in your sidebar.
Assignment: Write your back cover bio.