AFProtected is a Dev Wiki gadget used to warn users when they are trying to edit pages protected by the abuse filter ID 1 (interface page protection) and abuse filter ID 3 (Custom- prefix protection). It adds a lock icon on the edit button and removes the options to save the page in the editor of pages which are protected by these abuse filters.
The notice shown on the edit page can be found on MediaWiki:Custom-AFProtected-editnotice and can be translated by adding subpages of that page with the language code (for example, a Russian translation would go to MediaWiki:Custom-AFProtected-editnotice/ru.
See also
Text above can be found here (edit)