It means someone died because they couldn't breathe. Examples being a crushed trachea, strangulation or hanging.
respiratory failure means they, for some reason, were unable to get air into their lungs. Throat damage, lung damage, a severe allergic reaction causing the throat or breathing passages to become restricted, etc. it can also mean when a person simply stops breathing. As far as symptoms… failure = not doing what it should and respiratory = breathing — pretty self-explanatory there. Hope this helps.
It means for whatever reason your body stops breathing and then you are dead ~~
It means you can't breathe, basically, because your lungs or windpipe or any other part of your respiratory system can't work anymore.