I think that you can go for almost any course. I’d recommend to have some background in finance for studying SAP FI or SAP CO, so perhaps you shouldn’t go for these modules unless you are willing to make an extra effort of learning at least basics of financial accounting. Apart from FI/CO, you are well-suited to choose any other SAP module. For example, you can get started with our free SAP SD course (sales & distribution).
For an Engineering student with an IT background and Excel skills, the SAP course that would be most suitable is SAP Material Management (MM) or SAP Production Planning (PP). Both courses are related to supply chain management and would be useful for managing the flow of materials and resources in the manufacturing industry. In addition, these courses require a good understanding of Excel, which the student already has, making it easier to grasp the concepts. The courses will also help the student to learn about SAP’s ERP system, which is widely used in the manufacturing industry.