a minor in (subject)

Translations
второстепенная специальность в (предмет)
She decided to pursue a minor in psychology.
Она решила изучать психологию как второстепенную специальность.
Definitions
A minor in a subject refers to a secondary field of study that a student chooses to pursue alongside their major in college or university. It typically requires fewer courses than a major and allows students to gain additional knowledge and skills in a specific area of interest.