SAP HANA is an in-memory data platform that can be integrated on both on-premise, or in the cloud. It is an innovative platform that is best suited for performing real-time analytics and developing and deploying real-time applications.
Learning SAP HANA all by yourself might be difficult, so sources like Books, Blogs, Practice Exam which will assist you in learning.
If you have some good capital, you can get certified by some renowned institutes. But, they charge a hefty amount of money. Some institutes are SIEMENS, ATOS etc.