Hi Rajendra,
There are a lot of modules in SAP covering all aspects of a business such as Sales & Distribution, Materials Management, Finance, HR, Plant Maintenance, Quality Management, Warehouse Management, Production Planning, Project system among others. There is nothing like "appropriate functional modules". All modules are crucial for a business and so are important. SAP do offer a lot in each of the modules to keep your future & profile interested. 
If you are looking for a functional role then you need to select a module that excites you and start learning the basics of its business function. Understanding the business function is equally important with understanding SAP module.
As you mentioned you are more inclined in a manufacturing environment, typically you are preferring a SAP support kind of a role. This will require you to understand the client's business and continuously improving the system as per its needs.
Regards,