This is a Burp Suite extension which discover content with a smart touch. A bit like "DirBuster" and "Burp Discover Content", but smarter and being integrated into Burp Suite this plugin looks at words in pages, the domain name, the current directories and filename to help you find hidden files, directories and information you usually don't with a static dictionary file that brute forces its way on the web server.
For more information, please refer to https://github.com/pathetiq/BurpSmartBuster