If you installed DataFlex Studio following the defaults you can double click an SWS file in Windows explorer and the Studio will be lauched with the instruction to load the workspace from this file.
An SWS file contains the version number of the workspace and when this does not match the current Studio offers to convert the workspace. This is a great but not always desired feature. The DFStudioLauncher determines the workspace version and loads the appropriate Studio version (must be installed of course) instead.
Starting DFStudioLauncher standalone register this tool as the tool to be started when you double click an SWS file.