Honestly anything! There are 3 main campaign objectives: Awareness, Consideration, and Conversion. For Awareness, the goal is mainly to reach more people and get some brand awareness. For Consideration, we can select a Traffic objective to send people to your website, Lead Generation to get more prospective clients, we can even select Post Engagement or Video Views as a goal. Finally, for Conversion, the goal is to sell, in other words, these ads are made so that people can either buy a product or book a service directly after seeing the ad.