In short, it is a step towards automation.
The headless mode of the Google Chrome browser provides the ability to implement and run massive-scale web app tests, navigate from one page to another without human interference, validate JavaScript functions, and provide detailed reporting. The GUI of a program is referred to as the head. It gets the name headless because it runs without the Graphical User Interface (GUI). The headless mode can run on servers without the need for dedicated display or graphics. It provides the ability to control Chrome via external programs. The Headless mode is a feature which allows the execution of a full version of the Chrome Browser. All you Need to Know about Headless Chrome
