Working with Dashboard data sources
You can use data sources to define the information that must be displayed in a widget. For example, you can configure a column chart widget to display all the opportunities (entity) closed and won (group), by an account manager (dimension) and the total amount of the sale (metric).
Defining data sources is not required for all widget types. Some widgets, such as bar and column charts are used to define multiple data sources to compare two sets of data in the same chart.
To access the Add/Edit Data Source window: