In business, a "pipeline" is a source where products and services flow into a said business or company out to an eventual customer. What's in the "pipeline" could simply be anything from information, to processes, to services, or actual products. Since businesses don't want to create waste, a business will "pipeline" informatin, processess, services to actual goods to follow along a specific, established business process or flowchart, or workflow.
As with a real pipeline, like a gas or oil, a real pipeline has actual pumps, valves, and control devices. So does a business pipeline; but, a business one is more abstract. Still, it has these same devices, even if a business pipeline carries mostly information, how it's accessed or controlled or used to 'feed" a business in creating (manufacture) or providing a service (retail outlet).
A business pipeline is the flow of information or actual products, like a 'flow' of goods from manufacturing, generated by supply & demand - this connection btwn factory - retail store - and customer. This generates workflow whenever an item is manufactured, to a retailer putting it out on the shelf, to the customer purchasing an item is a business pipeline. The business pipeline flows and provides business to all three in all three directions, so it's called a pipeline.