The final line is sarcastic. It *is* hard. We have too many
  words in English that sound the same but are supposed to mean
  different things.

  And actually they DO mean the same things, when you take away
  the context.

  ''They're'' / ''their'' / ''There'' all mean:
  somebody/something/someplace that's NOT ME, NOT MINE AND NOT
  HERE.

  Easy. Means the same thing. Except grammar nazis, who love to
  mess around with Context. xD (I am a reformed Grammar Nazi from
  long ago but I have learned an easier way)