The "Export for Bibliometric Mapping" option will export a .CSV file which is formatted to be used with the openly-available VOSviewer software programme from CWTS Leiden (http://www.vosviewer.com/). VOSviewer is a software tool for constructing and visualizing bibliometric networks. These networks may for instance include journals, researchers, or individual publications, and they can be constructed based on citation, bibliographic coupling, co-citation, or co-authorship relations.
In order to use the exports in this way, simply download the VOSviewer tool from http://www.vosviewer.com/download and create a bibliometric mapping export from Dimensions for importing into this. The export for bibliometric mapping is limited to a maximum number of 5,000 results, and is only available for publications data.