The best explanation we can give you about a multi-channel ecommerce approach is a wheel with poles. In the middle of the wheel is the sale (or the product). On one side of the wheel there are the customers and on the other side is each channel that offers an opportunity to purchase. The whole point is to offer your customers a choice to purchase from you on whatever channel they like.
If you are not really sure how this multi-channel strategy works, here is one example that will certainly help you.
Let’s say that you are running a certain business and you have already established an online presence. You have built your own website and you are noticing that your sales increase constantly. After some time, the sales stop. If you ignore this change, your business may fail. You need to offer another option to your customers who are looking to buy your products. Take advantage of the popular marketplaces such as eBay, Amazon, Etsy, and others and promote your products there. Offer a third option – create your own Facebook store and attract even more potential customers. This is how multi channel ecommerce works.