Walter and Mama clash over how to spend the $10,000 in insurance money. Mama thinks communally about the money, planning to put most of it into a nice house in the suburbs where they can all get away from the ghetto. She wants to divide the rest between Walter and Beneatha, so that both of her children can pursue their dreams.
Walter wants to use the money to open a liquor store, as he thinks a successful business will pave the way for family prosperity and self-respect. Both Mama and Beneatha dislike this idea.
The deeper issue, as Mama understands, is that she doesn't trust Walter to be able to handle the money or to responsibly take on the role of head of the family he yearns to assume since his father died. He wants to be the family patriarch as the sole surviving male, but Mrs. Younger thinks he isn't ready for the role.
Nevertheless, Mama knows that if she continues to infantilize him and deny him opportunities to control his life, she will simply be replicating what the white world does to Black men, which is to infantilize them until their hopes dry up. She therefore gives Walter $6,000 of the money to control, both his and Beneatha's share, in order to show her trust in him and build his sense of self-worth. He loses the money, just as Mama fears, but also learns and grows enough from the experience to later stand up for buying the house.