It's mandatory for your Google Shopping feed to contain these fields: id, title, description, link, image_link, price, condition, availability, brand, and gtin. If your products don't have GTINs, you can use the identifier_exists attribute to signify that.

Online retailers submit feeds containing product information to Google Shopping. Since this product information comes directly from the seller, this means we're able to show the current prices, latest offers and current product availability.

They can include a product image, title, and price, plus your store or business name, all right in the ad. Merchant Center creates these based on information you include in your product feed so you don't need to create the ads yourself.