Folder Sync can terrify you by showing a blank screen:
BC thinks you don't want to see the files that don't need syncing (e.g. files that are already up to date on both sides), so it hides them. To unhide those files, press Peek
Other than Folder Sync, you don't have to worry about Peek in the beginning until you start using filters.
Peek allows you to turn off a filter. Down below, I have those sort of (okay, extremely) annoying Apple meta files that get split off when you copy from Mac to a non-Apple environment.
If you don't want to see files that begin with dot (1) you can set a filter with Session->SessionSettings->NameFilters. Set the filter to Exclude files matching the pattern of "dot anything", in other words .*. Star means wildcard here, similar to DOS/JS language. But now you can use use Peek to toggle the filter on and off.