Complex sentence: FlashDevelop is not a platform of its own, but rather acts as a code editor for the Adobe Flash Platform, therefore publishing a project into an SWF file that can be run in the Adobe Flash Player is the primary purpose of the editor.
Split into simpler sentences: FlashDevelop is not a platform of its own, and is a code editor for the Adobe Flash Platform. Publishing a project into an SWF file that can playback in the Adobe Flash Player is the primary purpose of the editor.