One of them wants to be a professional photographer, the other one is in love with pastry and the third one wants to become a writer.
In the story, they show us a great example of believing in ourselves and not just settling for who we 'naturally' are meant to be. For example, being cows, meant that they were only supposed to give milk, but in the story they show us how it was more important for them to pursue their dreams and set an example for the other animals. They demonstrate the importance of becoming who they wanted to be, by making their dreams come true. This was also how they brought happiness and fruitfulness to the animal farm!