Do you recall the Samsung Galaxy S5 Sport? Unless you own one, probably not. It's essentially a Galaxy S5 Active with a different name. The former is only available on AT&T. The latter is a Sprint exclusive.
Today the Galaxy S5 Sport's carrier has announced its Lollipop over-the-air update. Software version G860PVPU1BOC5 will bump the handset up to Android 5.0 and bring with it all the changes that this transition entails.
This update also includes reactivation locking, which requires entering security credentials in order to factory reset the device. Consider it one extra incentive for someone not to steal your device. Sure, if you've made it to this screen, then they've probably already gotten away with it. But keeping your phone un-wiped gives your tracking software a better chance of eventually hunting them down.
Really, this update is all about Lollipop, which arrived on the regular Galaxy S5 quite a while ago. At least your variant was built strong enough to survive the wait.