。
She studies hygiene as part of home economics.
Literal
She [topic-は] home-economics [of-の] one-part [as-として] hygiene-science [object-を] is-studying.
家政学 is an established academic field in Japan — 'home economics' as a university-level discipline covering nutrition, child development, family studies, household management, and clothing science. Several Japanese universities have full 家政学部 (home economics faculties); the field is considerably more academically rigorous than the school subject 家庭科. The compound particle ~の一部として ('as part of') situates 衛生学 ('hygienics, the science of hygiene') as a sub-field within the larger discipline. The whole sentence has the polished register of an academic profile or course catalog.