These settings influences the writability of feed header data. 

Open = Writable

Protected = Padlocked (you can't edit unless you click on the padlock. The lock is automatically set again if you refresh the page or leave the product page.)

Read-only = Locked (no manuel edit possible, unless an administrator changes the settings at this page. 

Unique* = Only accepts unique product numbers. 

PS: even if a field is Protected or locked, updates will be possible trough Excel import, or updates via integrations.  

Unique*

If you cannot activate Unique due to existing duplicates, you can identify these duplicates in the following way: 

1. In the product search under Selection. Click on Product. 
2. Under product number, click on "Has duplicate", then click on add to search. 
3. Click on the magnifier to get a list of these products and do the necessary steps of removing duplicate product numbers.

After this is done you can re-enter Settings, Product settings and activate the Unique function.