The stock item list screen has two (2) mode options available: 

Default mode option - This is a plain list view of the stock items on which the data in the columns is not editable.

Advanced mode option - This mode will enable the following options:

The data in the columns on the stock item grid can be edited (like you would in a spreadsheet).

Add the Export / Import, Adjust stock and Settings tabs.  

Advanced mode not selected 

The data for each of the stock items in the list can not be edited. You need to select a stock item and edit the details in the Stock item form. 

stock-items-default-mode

If the "Advanced mode" is not selected, the "Description" column will be listed in the Data band.   

To enable editing the data in the columns on the stock item grid, click on the Advanced mode button.

Advanced mode selected

If the "Advanced mode" option is selected, the Advanced mode button's caption, will change to Default. It will enable the following options:

The data in the columns on the stock item grid can be edited.

Add the Export / Import, Adjust stock and Settings tabs.

stock-items-advanced-mode

If the "Advanced mode" is selected, the "Description" column will be listed in the Left band.