'Product experience' can be understood narrowly, to mean only the experience of using a product. Usually, though, it's used to capture the idea that the user's perception of a product is influenced by factors beyond the core product itself.
For a physical product, for example, the product experience usually includes the packaging. Increasingly, it also includes the experience of an associated mobile app.
For digital products, the product experience increasingly includes the content consumed as the point of purchase approaches (for example, demos or trials) and training or support content consumed after purchase.