Great question! The short answer is: maybe. The long answer requires a little more information about your back pain: how long has it been going on, what positions/movements increase the pain, location of pain, intensity of pain, etc.
In general, biking could be helpful but is likely not the 100% answer to your back pain. Biking is a low load exercise that can increase cardiovascular health, improve joint mobility, regulate blood glucose levels, and improve muscle/tendon resiliency... all these things can help reduce low back pain. Ideally biking is combined with other things that can help with back pain: physical therapy, core strengthening, hip mobility, stretching, etc.