BASIS is not a programming language.
The basis is the SAP version of system administration. In most non-SAP organizations, "Basis" people are known as "system administrators".
Basis administrators are liable for guaranteeing that the SAP application server and applications are installed and configured properly and remain running smoothly. Depending on the organization, SAP Basis Administrator can also be accountable for configuring and maintaining the OS and information that SAP is running on, however, in several organizations, there are different system administrators liable for operative systems and databases that job with Basis consultants to tack together the total system.
ABAP (Advanced Business Application Programming) is SAP’s programing language. As a Fresher, you can opt for any of these roles as per your interest. But if you're fascinated by learning SAP Programming, choose SAP ABAP certification.