advanced course; postgraduate non-degree program
Refers to a specialized, non-degree course offered at some Japanese vocational schools, junior colleges, or universities for graduates who want further training without pursuing a full degree.
After graduating from junior college, she went on to the advanced course and studied for one more year.
Compound of 専攻 (senkō, 'major' or 'specialization') and 科 (ka, 'course' or 'department'). The term is a straightforward modern educational compound.