In most of the organizations, MM consultants are responsible to handle process consulting and SAP technical configuration for:
- Material movements
- Inventory activities (can include Warehouse Management activities)
- Procurement (purchase requisitions, quotations, RFx processes, Purchase Orders, Contracts, Goods and Invoice Receipt, and all master data involved in these processes)
- Interfaces between logistics and Accounts Payables
- MRP (work with PP consultants to properly configure this process)
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:
But, in some countries (like Brazil) MM consultants also have a strong role in determining how taxes are determined and calculated for incoming goods and services.
Hope this helps you!