Hey,
BCA is a three-year long undergraduate course that equips you with the skills that will help you in dealing with Computer Applications.
The basic eligibility criteria is to pass 10+2 from a recognized board with atleast 50 percent marks with Mathematics as one of the compulsory subjects.
The admission to different colleges is either based on  your performance in the entrance test or your score in 12th. It varies for different colleges or universities.
This course is designed in a way that will cover everything that you need to learn for the Computer Applications.
The study period of BCA includes various subjects such as Programming in C Language (Basic and Advanced), Networking ,World-Wide-Web, Data Structure, Advanced C Language Programming, Database Management, Mathematics, Object Oriented Programming using C++, Visual Basic, Programming using PHP, JAVA, Oracle, Operating Systems, Web Scripting and Development, and so many more.
Hope this helps you.
Good luck.