If your ambition is to become a Pharmacist then I would say anything to do with working with people where you can show communication, teamwork skills, time management, or empathy would be beneficial. Anything that can demonstrate that you want to help people! If your school has any science clubs, or any opportunities to visit science museums or workplaces.
What you really want to be demonstrating in your PS is your passion for the subject and show your personality!
Ask your teachers if they can assist you with any placements or extracurricular activities as well.