well - in principle, "Operations" transform resources (or data inputs) into desired goods, services, or results, hence creating value to recipients (mostly: customers). Two or more connected operations constitute a process, and are generally divided into four basic categories:
For each of these categories, efficiency is name of the game. This means that either the output is maximized (given certain resource inputs), or resource input needs are minimized for a desired output.
So for example for processing, operations problems can cover yield improvement problems, while for inspection, there might be the topic of automation (hence reducing input resource needs). And so on. You can draw a whole landscape of problems.