If it starts your car this most certainly does not make it fine without further insight. Given what appears to be a 15 year old battery this is the extreme end of longevity for a lead/acid battery. Remember though they are consumables.

All batteries age and this starts often before first use if they have been on a garage shelf in other than dry charged state. The ageing process usually caused by slow but steady sulphation of the plates in lead/acid batteries is often masked by regular use on an easy starting engine. It's still slowly loosing capacity though until out of the blue it will fail typically after the first freeze and despite being left on float from a battery charger/conditioner which is sub optimal in itself. Better to use car fairly regularly throughout the year and don't leave it on smart charger for long periods. My factory Banner battery, an often criticised brand, is still holding up well after over seven years but the car is used at least once every three weeks in the winter and far more often in the summer, and has a 12 hour top up on a charger every 2 - 3 months.

The capacity reduction which may end being a small fraction of original may still turn engine over but for how long? It will recharge very quickly, and show fully charged voltage but only an empirical load test at say the C/10 rate will reveal it's actual capacity. A useful guide I find is the standing battery voltage after a two to three weeks without use or charging. If it's dropped from fully charged 12.7 to 12.2 volts or less than look towards replacing. Please if otherwise in any doubt, change at six to eight years of age or sooner if you know it's been left for extended periods in partially charged state.