Using Secondary Dimensions
The Secondary Dimension feature allows you to define a primary dimension and then view that data by a secondary dimension within the same table.
The feature is available from the Secondary Dimension menu at the top of your first column of table data. For example, in the Referral Traffic report, the default dimension is Source. If you select a secondary dimension of City, then you see the cities from which the referral traffic originated.
Some reports, like the Overview reports, don't include the Secondary Dimension feature, and you do not see the menus.