Open Inventory → Products. The demo carries fittings and valves with real quantities on hand, received through actual purchase orders rather than typed as opening balances.

Open a product and check On Hand against Forecasted. Then open Inventory → Operations → Transfers to see where those quantities came from.

Multiple units of measure are enabled, so a product can be bought by the box and sold by the piece — the usual case in trading, and the usual source of stock that looks wrong when a system cannot express it.