The 'Product' dimension reports the name of the product in the hit. It is useful for implementations that use the products variable and want to see metrics around products, such as top sellers or most viewed. This dimension can intentionally be blank if you don't have any products on your site.
Populate this dimension with data
This dimension references the second part of the string in the products variable. Characters between the first and second semicolon ( ; ) populates this dimension.
Since this variable is based on a custom string in your implementation, your organization determines what the dimension values are. Adobe recommends that you establish a consistent naming convention for products. Classifications are available if you want to group products differently or provide a more friendly name. Adobe recommends using both the 'Product' and 'Category' dimensions.