Here's why:
* Definition: An explanation is a statement or account that makes something clear.
* Usage: We use "explanation" to refer to the act of explaining or the thing that is explained. For example:
* "I need an explanation for your absence." (referring to the act of explaining)
* "The scientist provided a detailed explanation of the experiment." (referring to the thing explained)
While "explanation" can sometimes be used as a verb (e.g., "He explained his reasoning"), it's much more common and natural to use it as a noun.