The commonly discussed flows are physical flows, information flows and documentation flows.

Physical flow : Can be the actual movement of goods and people
Information flow : Data flow in the system (system transactions)
Documentation flow : GRN, pick list, Delivery Order, Purchase Order

Then there's also financial/cash flow. This is more accounting related flow.

Physical flows are easy to notice. Same goes for documentation flows.

Both information flow and financial/cash flow are slightly difficult. Will need someone to do some process mapping to determine the end-to-end flows.

Your warehouse product flow determines your overall productivity and efficiency. Warehouse and distribution center layouts often include four areas: dynamic storage, static storage, shipping, and receiving.

The higher the productivity and efficiency, the more inventory can be processed. Indirectly, this also means the number of staffs required to process the same inventory volume may be potentially lesser. Thus, the extra staffs can be re-deployed for other activities.