Hello Pradeep,
I am new bee SAP HANA but here is my thought based on what what I have read & understood so far but I would encourage the experts on this board to fine tune this response or correct me where ever appropriate.It would be advantageous for you if you know any relational database and programming languages (like Java Script, HMTL5, etc) as it would give you a jump start and would be easier for you to understand how programming is done in SAP HANA.
And I am sure that most of the members would agree that learning new technology which has a great future is always a good thing.
It is not a mandatory for someone to know SAP in order to learn SAP HANA, but it would be great to know (or pick up as and when you can) SAP and SAP terminologies as eventually end up integrating SAP HANA to some other SAP system sooner or later.
There are lot of good blogs and other materials that you help you to start exploring SAP HANA. Please refer to Getting Started with HANA section at SAP HANA Developer Center, which would give you a great start.
Happy Learning.
Thanks,
-Prashant.