The realities of your practicum experience can vary quite a bit, depending on the field in which you wish to work and your placement within a program. If you want to become a teacher, for example, then your practicum is likely to take place in a classroom and you will have to deal with students and leading instruction. On the other hand, if you are looking to get into another field, such as healthcare or conflict resolution, then your practicum experience will be quite a bit different. In general, however, you can expect to be in an environment in which you can apply ideas and theories you have learned in class to real scenarios.
Just about any practicum experience is designed to provide you with an opportunity to see how the material and information you learn in a classroom apply to real world settings. This can be intimidating at first, but is often considered to be just as important to your education as anything you learn from a teacher. Your practicum experience is likely to vary quite a bit depending on the field in which you wish to work, though general expectations include exposure to new ideas and a better understanding of what you have learned.
If you wish to become a teacher, for example, then your practicum experience is likely to take place in a classroom under the supervision of a licensed teacher. This means that you will interact with students and may meet other teachers. Since you are in a classroom, you will see the instructor handle classroom management and organize activities to ensure that students stay on task. Your practicum experience may also include seeing how the teacher interacts with other professionals and parents, in order to better understand the ways that different social concepts affect education and teaching.
In other fields and professions, however, your practicum experience may vary quite a bit, especially in situations that may be especially stressful or difficult. Students interested in becoming healthcare providers, such as doctors and nurses, often go through a practicum in which they experience the realities of working in the industry. This can be quite difficult, but is important as it exposes you to certain facets of the workplace that may otherwise come as an unexpected shock when you complete your education.
General expectations for any practicum experience, however, should include a better understanding and awareness of what a particular industry is like. You can learn a great deal of information in a classroom, but not all of it is applicable to your professional future. After you complete a practicum, you are likely to have a much better understanding of what is relevant and what is purely academic. This applies to both information that you have already learned as well as new material in future courses.