。
Your medicine is ready, sir/ma'am.
Literal
[honorific-お]-medicine [subj-が] became-ready-[polite past-ました][assertion-よ].
The exact phrase a pharmacist uses to signal a prescription is ready for pickup. The prefix お on 薬 is the beautifying/respectful お (a gesture of politeness toward the customer). できる here means 'be completed/ready,' not 'can' — a common secondary sense. The final よ adds a light 'I'm letting you know.'