Proxy pages are used to simplify the structure of the repository and optimize storage for large catalogs.
Creating a catalog will use ten nodes per product as it provides individual components for each product that you can update and customise within AEM. This large number of nodes can become an issue if your catalog contains hundreds or even thousands of products. To avert any issues you can create your catalog using proxy pages.
Proxy pages use a two-node structure (cq:Page and jcr:content) that does not contain any of the actual product content. The content is generated, at request time, by referencing the product data and the template page.
However, there is a trade-off. You will not be able to customize your product information within AEM, a standard template (defined for your site) will be used.