Since the Hancom suite was included with your device, the system takes it as a 'stock' app. That's only warning you that MAYBE it's something the manufacturer uses for other things. In this case, not really, so it's safe to disable. Most of the time (and as long as your device isn't rooted), anything that isn't safe to remove cannot be uninstalled, only disabled (and should you need it again, just re-enable and done!). The data warning is because once you uninstall an app, any data that it saved might be gone, and if that data isn't backed up somewhere else (like cloud save files, for instance), you lose the data.