Your car is equipped with an automatic oil life sensor that tracks your mileage and vehicle starts to determine when your oil needs to be changed. You can find out more about how this system works in your owner's manual. If you have misplaced the one that came with your car when you bought it, you can download a copy by logging in here at the Honda Owner's website: http://owners.honda.com/vehicles/information/2015/Accord-Sedan/manuals
If your sensor is telling you it's at 51%, then you have 49% left on your oil life. How much longer it will last will depend on how much you drive every day and some other other factors. Based on your later message, and how much it has increased since then, it seems now might be a good time to call your dealership or regular mechanic to schedule a service.
If you don't have a regular mechanic, you can find an AskPatty Certified Repair Shop at http://www.askpatty.com/search/?type=all&m=30&q=&keyword= and they can help you maintain your Accord.