Can someone tell me how long will recovery take for back surgery?

Depends on Type. Could be a few weeks to a few months, depending on what type of spine surgery was performed. Ask your surgeon to go over the specific surgery he/she is proposing for you including the expected recovery course.
Varies . It varies a lot based upon the type of surgery you had. Some surgeries have very little recovery at all, even as low as a few days. Others, such as fusions, may take even up to 6 months to fully recover. If it gets beyond that, you may need some more testing to make sure nothing else is going on.