An economic model attempts to abstract from complex human behaviour in a way that sheds some insight into a particular aspect of that behaviour.
The following is drawn from the online EconModel glossary.
"An economic model attempts to abstract from complex human behavior in a way that sheds some insight into a particular aspect of that behavior. This process inherently ignores important aspects of real-world behavior, making the modeling process an art as well as a mathematical exercise.
The expression of a model can be in the form of words, diagrams, or mathematical equations, depending on the audience and the point of the model."