The modern pharmacy provides many more services than just filling prescriptions. The majority of people coming in to your premises will be aware of some of the extra services you provide but it is unlikely that they will know about everything you do. An information screen can help you to spread the word about what you do in a lively and informative way that will get more attention than posters and notices.
An information screen is also a great way to tell people about over-the-counter products and promote upsales by prompting them to remember items they might need as well as their prescription.