Feed labels let you advertise all products with the same feed label in a Shopping or Performance Max campaign. You can select only one feed label per campaign. Feed labels allow more flexibility in campaign targeting. For example, product data sources using the same language could be given the same feed label, making it easier to target those product data sources in one campaign.
The feed label you select will determine which product data sources from the selected Merchant Center account can be advertised in this campaign
Feed labels are available only during the creation of a new data source if you have "Advanced data source management" enabled under “Add-ons”.
Instructions how to enable Feed label
In your Merchant Center account, click on the Settings & tools icon in the top right.
Click Add-ons.
On the "Discover" tab, find Advanced data source management and click add. If you already have the add-on installed, it will be available in the "Your Add-ons" tab
The feed label will now appear when creating a primary data source.
Add a label to your product data source in Merchant Center
Once a product data source is created, you cannot modify the language or feed label.
In your Merchant Center account, click on the Settings & tools icon in the top right.
Select Data sources.
On the "Primary sources" tab, click Add product source.
Add your data source information and scroll to the bottom of the page to view the "feed label" setting next to the "country", "language" and "marketing methods" settings.
Click on the pencil icon next to the feed label option
In the empty field, enter a name that helps you easily categorize and identify your products in Ads campaign (up to 20 characters). The supported characters are A-Z (in upper case only), 0-9 digits, hyphen or underscore. The feed label must not include any spaces. For example: "DE"
Click Save