When you begin the synchronization process, Syncopation determines which music or video tracks need to be added or removed from the iTunes music library to synchronize it with other libraries. The required changes are shown in a preview panel which lists track additions, updates, and removals as well as playlist additions and removals.
The preview panel also gives you the ability to control which operations are performed by toggling the checkbox next to each addition, change or removal. The operations are shown in a tree. Enabling or disabling a checkmark higher in the tree will effect all changes under that item.