How are product groups used in Shopping campaigns?
- To bid on organized inventory in an ad group
- To create a list of keywords used to target Product Listing Ads to shoppers
- To bundle items sold as a package, like a camera and tripod stand
- To organize products within a data feed
How are product groups used in Shopping campaigns
Inside a Shopping campaign’s ad group, you’ll work with your inventory to place bids using product groups instead of keywords. A product group is just a subset of your inventory that you define, and all the products inside it use the same bid.
Read more here: https://support.google.com/adwords/answer/6275317?hl=en