This insight gives you the ability to track the total sales from your Shopify storefront and see the trends in the given time period. The total sales and net sales in the given time period are represented as metrics in the insight.
See a surge in sales? It could be because you added a new product to your store, sent out a marketing campaign with discounts or just started advertising in Facebook or Google. Identifying the reason for surge in sales will help you focus your efforts and money on the right marketing channels. If you see a dip in sales, make sure your storefront is up and running without any issues, also make sure your inventory levels are right so that users don't see a "sold out" indicator next to your products.