Hey,
You can either go for BA in Psychology or B.Sc in Psychology. Both of them deals with the behavioural functions of the human beings and also animals. The only difference is that in BA Honours in Psychology you stress more upon the theoretical concepts while B.Sc in Psychology stresses more upon the practical aspects.
The basic eligibility criteria is to pass 12th board from any recognized board with relevant stream . The admission procedure is different for different institutions as some accept your 12th scores while some conduct their respective entrance examinations. Some of the colleges offering this course are:
The University of Delhi,New Delhi
Jamia Milia Islamia,New Delhi
Presidency College,Chennai
Lovely Professional University
Hope this helps.
Good luck.

Khushi, if you want to take up Psychology as a subject in your Bachelor's degree, you can opt for B.Sc Psychology. If you can help us with the State you belong to, we can help you with the admission process of the colleges that offer B.Sc Psychology for you.