When creating a picklist, you are able to click on the figures within the On Hand column and view stock levels for the line item selected.

This will open the Stock Enquiry panel for the corresponding item, as in the example below:

The first tab in this panel shows you your current stock availability at your store(s), and it will also show you the Supplier Stock Availability, if the item is from a SIM Supplier.
The second tab shows you any units of this item that are on open purchase orders or transfers.
The third tab shows you any customer orders that this item is committed on.