The trigger “Profile cloud data present” executes after data has been sent from profile cloud. Generally, Web data collection-data is stored in the user´s browser. In some occasions, information from the profile cloud has to be available to serve the purpose of the event. Example of that can be geo-location data or attributes that may come from other data sources and has not yet been synced with the user´s browser.
If your event needs information to be present that is not stored locally in user´s browser, this trigger will make your event execute right after the reception of these data.