MFC stands for Microsoft Foundation Classes.
It is Microsoft's Win 32 application framework for writing Microsoft C/C++ and Visual C++ applications and is made up of a collection of classes written in C++.
There are MFC classes for using GUI elements, accessing databases, handling Windows messages from other applications, and dealing with keyboard/mouse input.
Win32 is a library made of data types, variables, constants, functions and classes that are used to create applications for Windows.
A Win32 program uses a central function called WinMain. To support international characters, Microsoft provides another version, called _tWinMain.
To implement its functionality, the MFC is organized as a hierarchical tree of classes, the root of which is CObject.
Instead of creating an application using "raw" Win32 classes and functions, the MFC library simplifies this process by providing the framework which is a set of classes, functions and techniques used to create an application.