MVC splits the software in three parts: The model, containing the data and the software that makes the data usable; the view, which is what is presented to the user in a visible way; and the controller which takes user input and manipulates the view and the model.
To put in in another way: The model is connected to the user's mind; the view is connected to the user's eyes; and the controller is connected to the user's hands.
Note that the user could just as well be another piece of software.
The point with MVC is that by separating the functionality maintaining the code by debugging, changing and adding features becomes easier.
The concept was introduced in 1979 and was first implemented in the programming language Smalltalk-80 developed at Xerox PARC.