So you might say you have a biology degree, or your major is biology; or still you have a bachelor degree.  Simply as that. 

    This meaning you have finished the undergraduate studies, and have a diploma already.

     Thus, if you are studying at the university you might say you are an undergraduate student.     Or if you studying post-graduate studies you are a graduate one, since you might have finished the undergraduate studies (so you are a graduate, got it?). 

     Usually people ask you "which is your major?" meaning which is your chosen career, wether you are studying or your have finished college studies.

     If doubt persists, please ask again and we will try to clear it up.

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     Recently, you can be a graduate degree in some courses too, in less time.

     These are the so called associate degrees (back in Brazil, cursos de técnologos mais afetos à carreiras tecnológicas como petróleo e gás, por exemplo).   They are taken in average in two-three years.