It's quite simple. Someone doing a university/college degree has a "major" area of study which is the main degree they are pursuing (ie., history, fine arts, biology, etc) but they can also have a "minor" area of study in something entirely unrelated. The number of courses needed for the minor is not nearly as many. So, for example, my brother majored in Chemical Engineering but minored in the Russian Language. It allows a student to broaden their learning and tailor it to their vision of their future without going too far off track from their main purpose.

"En el caso de Major, se refiere al área general de estudio, como puede ser Ciencias sociales, ingeniería o economía. Y Minor a la especialidad en concreto que se ha completado durante la Bachelor degree, así como ingeniería mecánica o economía financiera." si quiseras saber mas informacion ve a este webiste amigo ! Suerte !