The eCommerce is a complete online store solution that contains both a catalogue front-end and an administration tool backend.
This integrated e-commerce system will allow you to sell anything you like through it, whether it be a guide book or a car. You can create as many categories as you want and sell as many products as you want.
The e-commerce system is like another business in its own right as the possibilities are endless. If you don't have any products to sell yourself, then all you need to do is source where you can buy products from and then sell them on through your site at a profit.
AS well as using this to sell any of your own products, individuals/shops etc might want you too sell their products through this system if they haven't the ability to trade online - you can of course charge them a fee, whether it be a fixed monthly fee or on a commission basis.