After you have selected your initial run options, a preview of the actual synchronization will be displayed. Pay special attention to files that you think ought not to be "recopied"; their sizes on Folder A and Folder B could be different or their modification date/times could be different by more than the value you allowed in the previous "initial run options" dialog.
What happens next depends on which button you click.
OK - Saves your initial run options, asks if you want to start the task (usually, "Yes") and asks if you want to enable the task to allow the scheduler to run it automatically.
Change Initial Run Options - Allows you to change your initial run options to include/exclude more files from the initial copy step. This button will be visible on the Preview page only until you run the task for the first time.
Refresh - Refreshes the preview page with more recent information.
Cancel - Closes the preview window and leaves your new synchronization task disabled. Before enabling or running your new task, you should use the "preview" option to make sure all connectivity is in place and that synchronization will be occurring the way you intend it to happen.
More information about the preview dialog can be found in the "Synchronization Preview" section of this documentation.
