When you offer a product for sale on the Redbubble marketplace, the terms are up to you, whether commercial (like price and product type) or promotional information that helps your products get discovered by your customers like tags, title, and description. When you choose to advertise your products off-site, you are choosing to send information about your product to third-party advertisers who have algorithms to help surface relevant products to your potential customers who are searching or browsing their sites.
Each ad platform has its own set of rules and guidelines to ensure that the most relevant, appropriate content is shown for a particular audience. This automatic, feed-based advertising is referred to as off-site marketing.