Complex sentence: That is language talking about language, for instance the American Psychological Association's DSMIV manual tells which terms have to be used in talking about mental health, thereby mediating meanings and dictating practices of the professionals of psychology and psychiatry.
Split into simpler sentences: That is language talking about language, for instance the American Psychological Association's DSMIV manual tells which terms have to be used in talking about mental health. Mediating meanings and dictating practices of the professionals of psychology and psychiatry.