Humans.txt is an initiative to know who's behind a website. The idea is a simple unobtrusive method of inserting a .txt file and a string in the sites header to point out the .txt file.
This plugin makes installing the .txt file and header string easy and automatic so Joomla designers don't have to worry about manually editing template files. All you need to do is edit the humans.txt file, add your information, install and turn the plugin on.
You can read more about the Humans.txt initiative at http://www.humanstxt.org.