Metadata is a field for updating your 

  • Data that provide information about other data.
  • summarizes basic information about data, making finding & working with particular instances of data easier.

1. Before want to update or import via stock sync, must create a custom field for every product in the WooCommerce store first.

2. Once created, can map to stock sync and enter the metadata key value that you created for all the products in your store. The products that wanted to import or update should have the metadata key if not it won't update it. 

3. If it didn't create the metadata key in your store yet. Can enable this option auto to create new metadata if not found. So, it will automatically be created for those products that do not have the metadata key. 

For example:

Created a metadata key as new_data for all the products in store, just fill in the metadata key as new_data to update or import the field. 

Mapped the column name according to your feed file and enter the value of the key that was created for the products.

If didn't create the metadata yet for some products in your store then can enable the auto create new metadata if not found option.