SAP BASIS is like an Operating System for R/3. It can say that SAP BASIS is a middleware between ABAP/4 (Advanced Business Application Programming) and the computer Operating system. SAP is ported it to client/server environment. SAP created BASIS. Creating BASIS enabled ABAP/4 code to run on other platforms as well. Without SAP BASIS programs SAP ABAP/4 programs cannot run. It can relate SAP BASIS to ABAP/4 programs, like Windows is to Windows programs. Thus, SAP ABAP/4 programs run within the protective SAP BASIS environment. They are not executables that run on an Operating system. Instead SAP BASIS reads SAP ABAP/4 code and intrepretes it into Operating system instructions. SAP ABAP is a high-level programming language created by the German software company SAP. It is currently positioned, alongside the more recently introduced Java, as the language for programming the SAP Application Server, part of its NetWeaver platform for building business applications. The syntax of ABAP is more similar to COBOL. Now it is ur decision to what u will do for right career. U may ask to ur near persons or consult to other persons who r ur nearby. Also make search on the net for more information.
I am also fresher and im now landed in SAP BASIS. If you want to do development work then you can choose ABAP, or if you want to do support work like administration work you can choos BASIS