Typically in a business setting an agenda is a list of topics to be discussed in a meeting.
One can also have an agenda that is a list of tasks to be completed.
Usually the tasks or topics are organized into a logical manner.
Sometimes an agenda is an underlying purpose for a behavior. For example a politician may talk about supporting one side of an issue and then vote for the opposite side as a part of a plan to keep popular support while still promoting the ideas he or she has of their own. Their own ideas are their 'agenda'.
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