mm in short refers to Google dorks or Google hacking, it is used to search for specific and potentially vulnerable information on the Internet. In itself is to use operators and advanced search parameters in search engines such as Google, Bing or Yahoo to find sensitive information or identify potential vulnerabilities in websites or applications. You can find hidden pages, sensitive files or misconfigured web servers that may be exploitable, etc.
For example ...
1. filetype: to search for specific file types (e.g. PDF, DOC, XLS)
2. inurl: to search for specific URL patterns
3. intitle: to search for specific page titles
4. intext: to search for specific text within a page
5. site: to search within a specific web site
Using these operators in combination improves and makes the search more accurate.
I hope it helps you