The Print output typically contains an Overview map. The source of the Overview map is a data frame called ‘overview’ in the ArcMap document used as basis for the ArcGIS Server Map Service that generates the Print documents.
In the ArcMap Layout view, it is possible to position and size the ‘overview’ data frame. The extent of the ‘overview’ data frame specifies the extent of the Overview map.
See chapter How to Print an Overview map for details.