About Author section is an area in theme/template which displays the basic information about the author of the blog’s post (screenshot).
Note: This will appear only if you have added biographical information about the author in profile settings pages.
Go to the admin area of your blog where all the basic information about you and your blog are there. Search for the About Yourself section in the page and write something about yourself in Biographical Info area.
Do not forget to save the changes.