If you have inventory tracking enabled for your store, you can configure the inventory settings for this product. If inventory tracking is disabled, there will be a notice at the top of the page. You can enable it by going to Settings -> Inventory Notices.
This is the number of items you have in stock for this product.
Update Inventory when it reaches this level:
This determines how low your inventory level must be before any action is taken.
This shows the current status of the product, whether it is available or back-ordered.
When available qty reaches the update level qty then:
After the update inventory level has been reached, this is the action that will occur. The menu choices are:
"Remove product from store" - This disables the "Active" field on a product so it will not show up in the storefront (useful for one-of-a-kind items).
"Leave product on store, do not track inventory" - Inventory tracking will be ignored for this product regardless of quantity.
"Show product as back-ordered, allow purchase" - This flag the product as back-ordered, but customers can still purchase it (useful for short back-orders).
"Show product as back-ordered, do not allow purchase" - This flags the product as back-ordered, and removes the “Add to Cart” button for it (useful for long back-orders).
When an item is back-ordered, you can leave a notice for your customers when they view the product. For example, you can write: "This item is back-ordered until November 8th, 2011."
If product options have been added, you can specify the quantity and SKU number of each option.