Hello,
I am beginning my answers one by one according to your questions below:
1. Which HANA module I have to learn, because till now I was in SAP MM tool & as Functional consultant.
Ans: As you are in SAP MM and Functional consultant then you can select any of the HANA modules which you think you can learn and build a career easily.
2. Which channel is easy to learn SAP HANA.
Ans: For this you can opt for SAP HANA online and offline courses. I hope this is something you are asking.
3. By learning SAP HANA, will it affect my current technologies (SAP MM)?
Ans: No, not at all even it only enhance and build your skills more.
4. To learn SAP HANA what is basic knowledge I need? (Ex: SQL, JAVA & C knowledge is mandatory)
Ans: To begin learning SAP Hana, you should have knowledge of Database Concepts and some basic knowledge of SQL is important.
5. Now I am working as functional consultant (SAP MM). Now which technology is better to learn HANA or ARIBA?
Ans: In my opinion SAP HANA is better based on your experience with SAP MM.
6. To move SAP MM to SAP HANA my current SAP MM Experience will be useful or not?
Ans: An experience in SAP MM or in any other field is always useful. You please move on as you wish and best of Luck!