In versions of the OS from v9.0, all executable files (exes and libraries) are built on the Symbian emulator to epoc32\release\winscw\udeb\ (or urel\ for release builds). This location is the equivalent to \sys\bin\ on target devices.
Resource files and other non-executable files are built to the location specified in the mmp file below epoc32\release\winscw\ udeb or urel \z\, for example, epoc32\release\winscw\ udeb or urel \z\resource\apps\ for GUI application resources.
A copy of the built resources etc. is also put under epoc32\data\Z\, which is used when building for any target, Symbian emulator or ARM. Because the same resource files apply to all build targets, it makes sense for them to be located in a common directory.
To run an executable file, start the Symbian emulator epoc32\release\winscw\ udeb or urel \epoc.exe, and run the program from whatever shell program the UI being used provides.