Alright, so I've watched some people on the internet defeat the ender dragon then go to get the dragon egg. After that, there was some stuff written on the screen but they skipped it because it was too long. I just wanted to know what's it all about. P.S. I know I can do it myself but I'm too lazy.
The text at the end is the end game screen. It's basically a lot of nonsense but has led to a lot of speculation of what it is and what it means. You can read it in detail on the wiki here. There are plenty of theories but, all in all, no one truly knows the link between the 'End Poem' and the game although on the wiki in the trivia it does say:
The Final Line of the Poem, "Wake Up.", may be a reference to the creepypasta of the same name, and/or Herobrine's association with the quote.
Which is one of the many theories you may find buzzing around but as I say: No one truly knows what it all means except for perhaps the author himself, Julian Gough.