The code queries the registry for the MSBuildToolsPath value in two versions (4.0 and 14.0) of the MSBuild tools path using the reg.exe command.
Alternatively, in two sentences:
The code uses the reg.exe command to query the registry for the MSBuildToolsPath value in two versions (4.0 and 14.0) of the MSBuild tools path. The expected output is the value of MSBuildToolsPath for each specified registry path.