Manufactures are New to 15.1. You can keep track and associate Items with a Manufacture.
To manage them Navigate to the Items View and click on the "..." button on the top right of the screen:
Select Manage Manufactures
When you select "Manage Manufactures" you will see this view. Click [Add Manufacture]
Click [Add Manufacture]
Type a Name and click ok
The manufacture dropdown will now show up when Editing Items