Hi Naruto Senki,
That isn’t a specific question, but requires knowledge of Unreal Engine’s basics, UI and programming. I’ve already made this system as a plugin and put it on FAB:
The documentation gives you an idea of how it’s implemented. You can also buy it to study the blueprints and C++ material in depth. The system is ready to be used in games as well.
The component of my “Status Effects Plugin” can be set up as a health stat, or literally any stat you come up with. “Damage” (aka subtracting X from a stat) is done directly through that component.
A death event can be set up on the actor you attach the component to. The status effect component broadcasts a delegate when a stat reaches 0. Your actor can listen to that event (see the documentation) and process its death event logic when health reaches 0.
The UI is set up as a listener as well, automatically responding to changes on the status effect component.