Public - Your title photo and name will be shown in public database. Your full profile will be shown to anyone.
Private - Your photos and name will be hidden from public, you will be listed as 'Private'. Your full profile will be shown only to authorised users.
Hidden - Your profile will not be listed in database. Your full profile will be shown only to users in which ads you apply. Only you decide who can see your profile.
In any case, all profiles, photos, videos and other content is completely hidden to Google, other search engines and not authorized users.