This quote shows that George is confident that they will have a destination in life. They will live off their own land with no worries. This makes Lennie happy, because he wants to tend the rabbits.
"We're gonna have rabbits an' a berry patch."
Lennie wants to leave the ranch soon after he meets Curley's wife, but George explains to him that they must stay until they have enough money for their land.
"You an' me can get that little place, can't we George?"
After Candy exclaimed he has money and would pitch in to help out the farm if they'd let him work there, filled George with hope. He kept repeating to himself in a soft voice, "I bet we could swing her," with his eyes lit up.
"An' live on the fatta the lan."
Lennie tells Crooks they are going to have their own piece of land, but he didn't believe him. After Candy walks in and tells him they they have it all planned out. Crooks starts to say he could work there.
After Lennie killed Curley's wife, Candy was worried about the dream they had.
Before George had to kill Lennie, he told him to look across the lake and tell him to think about their dream.