Salary for SAP MM professionals totally depends on the job profile, educational background, and experience in the respective domain. So, various job profiles for Sap's module, SAP MM is like MM Engineer, SAP Testing(SD/MM/FI), SAP MM - Materials Management-Configurator, SAP Support Analyst (FICO / MM /SD), SAP MM Consultant, end-user and so on. At, fresher level you can expect the salary as 3 to 4L per annum. And if you are experienced in this domain then it'll differ as per your year of experience and your knowledge/skill in SAP MM. Still, you can expect 10-12L if you have worked for 2 to 3 years in the same domain.
If you want to learn SAP MM from scratch, then here's the right video for you:
If you are more into reading, then do check out this material provided by Intellipaat: