ArcGIS Desktop is a GIS software suite (please see Geographic information system).
More information about the software can be found at the software manufacturer's website: http://www.esri.com/
Please also see ArcGIS.
There is a campus license for ArcGIS at Lund university. This license is managed by the GIS Centre at LU: http://www.gis.lu.se/english/software.htm
For help with using the software, please talk to your teacher, or contact the GIS Centre at LU: http://www.gis.lu.se/english/contact.htm