The majority of the SAP HANA software stack was written in C++. In fact, when you compile SAP HANA objects, they do in turn become C++ code, which is one of the reasons why HANA is so fast. The Predictive Analysis Library and Business Function Libraries are also written in a HANA-specific variant of C++ called L-Language, which provides memory protection.
Certain optimizations have been made using C and machine code, which is common for many databases. In addition, a lot of the tooling for HANA was written in Python, for ease of writing and adaption.