As an adjective:
* The professor gave an explanatory lecture on the theory of relativity. (Describing the nature of the lecture)
* The instructions were clear and explanatory, making the project easy to understand. (Describing the instructions)
* The article provided explanatory details about the recent events. (Describing the article's content)
As a noun (less common):
* The explanatory was helpful in clarifying the complex concept. (Using "explanatory" as a noun to refer to something that explains)
In phrases:
* The book offers an explanatory analysis of the historical context. (Used in a phrase to describe the book's purpose)
* The artist provided an explanatory note for each piece in the exhibition. (Used in a phrase to describe the note's purpose)
Let me know if you have a specific context in mind, and I can help you craft a more fitting sentence!