So what is ABAP development and how is it used in SAP? In its simplest terms in order to create the SAP system itself, first, a 4th GL programming language was created in C called ABAP. This stands for advanced business application programming, well the actual meaning is in German but this is the English translation.
Once the ABAP development platform was created the SAP system was then entirely built from the ground up using it. Therefore if you are interested in development/programming within an SAP environment you need to learn ABAP. It is a fairly straight forward language to get to grips with and is basically a database language that allows you to select, change and display data using various commands and built-in tools such as ALV. Once you have a good understanding of the language you will not only be able to create new functionality for your SAP instance but also understand and change the existing code which makes up the standard vanilla SAP system.