Sales by Product Report shows the quantity of products sold over a given time period.
If you are selling bundles, then this report will show you the number of components sold as part of bundles as well.
Direct Sales through orders: This is the total quantity of products sold directly in your orders. It includes normal products as well as bundled products
Sales as components of bundle: This is the total quantity of a component sold as part of a bundle
Total sales: Direct Sales + Sales as components of a bundle