The Assets tab lists the Assets that were bought under this Purchase Order. You can open an asset record by double-clicking it in the grid.
Typically, this tab lists the Assets automatically created when you "receive" the PO items by using the appropriate workflow action configured by your Alloy Navigator administrator. Another way to link an Asset with the Purchase Order is to select this PO in the Purchase Order field on the Finance tab of the asset record (either directly or by using a workflow action).