SongKong uses data derived from acoustic analysis of the actual song from AcousticBrainz. Enabling this option enables the options set on the Mood tab, this option is only available if you have a SongKong Pro license.
SongKong Pro can use acoustic analysis to determine additional features of your songs. With other solutions the software has to listen to each song to calculate the acoustic analysis, this is time consuming and CPU intensive. But SongKong Pro does not have to do this, the songs for nearly three million songs have already been analysed and results of the acoustic analysis is already stored with the song in the Albunack Music Server, so there is no additional time required to add fields calculated via acoustic analysis.