Hello chailsi,
 
  Bachelor of computer application is a course with duration of 3-4 years , normally 3 years in most of the universities.
 
  Basic criteria for being eligible for BCA is qualifying 10+2 or equivalent examination with 45% marks in any relevant stream with English as a subject from any recognized University.

  Also entrance exam is conducted for admissions.
So basically you have to gain more than 45% so that you can apply for BCA.

Thank you!!