You are looking at a dashboard. A dashboard doesn't have any data associated with it, it's just a container for other sheets.
The data and calcs etc live within a worksheet, which you can see the names for in the pane in the top left.
As Tom said - you need to be in a sheet to access the data pane. Select either the "performance" or "Forecast" tabs from the tab choices below. That should give you the data pane.
Typically, once a sheet is included in a dashboard, it is usually best practice to "hide" the sheet from the tabs to manage clutter. You can access the same sheet from the dashboard, if you see the left side you will see a list of sheets being used, you can right click one of them and select "go to sheet" .