The location bar, or address bar, in Firefox displays the url of the website that you are visiting. The website is normally displayed without dashes and contains the protocol, the subdomain, the domain name and the path. A less confusing way especially for novice or insecure users would be to divide the url into different parts.
This is what the locationbar extension for Firefox is doing. It removes the protocol from the address bar, lightens the color of the subdomain and presents the path in a breadcrumb display style. This makes it far easier to recognize the url which is especially good to detect if you are on a fake website.
Several options can change the appearance and display of the url. It is in my opinion useful to remove that the https protocol is not shown as well. This is important to detect fake websites.