Hello Aspirant,
Bsc environmental studies is a 3 year degree course. This course helps you to improve and grow your personal skills in ecology,  natural resources,  pollution monitoring,  environmental impact assessment and much more.
The basic eligibility criteria to do this course is that you should have passed 10+2 from a know board.
There are many universities providing distance learning for this course . Some of them are
NIMS University,  Jaipur
MKU University,  Tamil Nadu
Himalayan University
Jaipur National University
You can apply to these universities through offline or online mode.
The average yearly fees would be 20000 to 25000 depending on the university.

Hope your query was answered.
Thank you.