When I bought my car it showed similar faults when looking at it at the garage. Was just a low battery, once charged it didn't appear again. Presumably you car doesn't start or lights dim etc when you try to start? Also assume if you have radio on without engine running it shuts off after 3 mins with a warning it is conserving battery power? All these point to the battery. You can check battery voltage with a cheap multimeter - it should be around 12.5v and around 14.5v when the engine is running, which shows alternator is charging. It could be the alternator at fault, but chances are at 8 years old it will be the battery.
Check the type of battery needed - if you have start/stop you will probably need an AGM battery. There is some info on here about swapping the battery and possible issues that can arise, so worth a search. Also, you will need to reset the windows and parking brake, which is simple stuff. New battery should be 'coded' to the car, so it knows it has a new battery, but many, inc myself haven't done this, without any obvious issues, as the Battery Control Module should resets itself eventually.