This template has been copied from Wikipedia: Template:lowercase title.
If written to the beginning of an article, it allows you to make the first letter of the title lowercase.
This is needed in special cases, when starting the title with an uppercase letter otherwise would be confusing or incorrect.
Sadly, the effect only works on the page itself. For technical restriction reasons (of MediaWiki), the list of pages in a category still shows such a page starting with an uppercase letter.