To understand the keyword, you must first understand how old-school web servers work.
If someone uploads a pirated copy of Bhoothakaalam (e.g., Bhoothakaalam.2022.1080p.mkv ) into such an unprotected folder, and a search engine like Google indexes it, a user searching for "index of" bhoothakaalam will see that raw list of files. index of bhoothakaalam