how do you fix the light that says 'service past due B1? what does that mean?

Hello, your maintenance minder will recommend needed maintenance at specific intervals calculated during "normal" vehicle use. The "B" is saying you need an oil and filter change, and a "minor" service, including a brake inspection, parking brake adjustment, checking all the chassis and powertrain components, fluids, filters, tires and air pressure. The "1" says you need a tire rotation. Any good repair facility can turn the light off when they perform the maintenance. If you do it yourself, the owners manual will show you how to do it also.