It's the summary of what they feel. It was their pov about the things that they had no control of. It was simply asking for understanding. It lies between the lines. That they were sad and sorry of what happened, but they can't voice it out, and there's nothing they can do to change it. So they put in a song. It also symbolizes their love for the fans. That they appreciate the things that the fans gave. No matter how little or ginormous those things are. And for that, they are grateful. And I, myself, is also grateful to you, EXO.