For students who want to obtain an MBBS degree, most schools require that they take some form of an entrance exam. The exam covers basic science aptitude and particularly aptitude towards the study of medicine.
The MBBS degree is a common medical degree in countries outside the U.S., particularly in schools with UK style degree programs. It qualifies the participants to practice medicine as doctors. However, it is a general course of study, and if a student wants to specialize, they have to go back to school to get an M.D. degree. When following that course of study, the student can then specialize in a particular field.