It describes something that explains or clarifies.
Here are some examples:
* Explanatory notes were included with the instructions.
* She gave an explanatory speech about the new policy.
However, "explanatory" can sometimes function as a noun in a specific context, referring to an explanation or a statement that explains something.
Here's an example:
* The professor's explanatory was clear and concise.
So, while "explanatory" is mainly an adjective, its use as a noun is less common and typically found in specific situations.