In Office 365, a resource account is a non-person account that can be classified as either "room" or "equipment". Examples can include meeting/conference rooms, audio-visual equipment, or vacation calendars. Individuals must be granted permissions to interact with a resource account. More details.
A feature in Office 365 which allows you to take some action when a message arrives into your account or when you are sending a message. Examples of potential actions include move/copy/delete, mark with a category/read/importance, or forward/redirect.