While they were resting in the woods for the night, George tells Lennie that if he gets into any trouble, to travel back to these woods and hide behind the bush near the river.
George is telling Lennie about the land they want to obtain to achieve their American Dream. Their american dream is to own their own land and be free to do what they want.
In the shed where the workers would sleep, Lennie has made enemies with their bosses son Curley. Curley doesn't like men larger than him so he likes to fight them to prove he's not weak.
Lennie accidentally kills Curleys wife by snapping her neck. Lennie was afraid that George would find out that he was talking to Curleys wife and wont let him tend the rabbits.
Later on, the rest of the workers including George, Candy, and Curley find his wife's lifeless corpse. They all go out in the woods to find and kill Lennie but George knows where Lennie hid. Once he finds him he procedes to pull out a gun and mercy kills Lennie.