On the Sales tab, in the Reports section, you'll find a basic overview of your revenue for the selected period, as in all other sections in the Reports tab, you'll see data based on the End of Day setting in Place settings on the Place tab.
If you manage multiple businesses you can choose what data you want to display on the top-left menu (1). You can also set a specific time period (2), you can also export your data from both the chart and the table (3), the export is generated in .xls format for Excel. The charts on the Sales section work like the charts in most other sections in the Reports tab, and you can learn how to work with them on this article.
In the table you see earnings, average per client and number of people. On the chart you can use the checkboxes (4) to see only the individual payment types you have in your business.