Refers to pharmacy as a field of study or academic department, not a physical pharmacy (薬局).
彼は大学で薬科を専攻している。
He is majoring in pharmacy at university.
I want to go to a college of pharmacy.
pharmaceutical college; college of pharmacy
Compound of 薬 (medicine) and 科 (department/subject). The reading やっか is a contraction of やくか.