You can do following courses after your 12th:-
MBBS: It is a bachelor's course in medicine and surgery. It is an undergraduate course to become a doctor and you have to appear for NEET exam for this course.
BDS: It is a bachelor's course in dentist surgery and you will become a doctor on its completion.
BSC: Bachelor in Science is a 3 year course in the stream you want like biology, chemistry or physics or agriculture( 4years), etc.
Hope this helps. Thank you.