Sofia is made to clean and work in the laundry while in prison. Her mental state is extremely poor. Her friends believe she will not survive her time in prison.
To cope with life in prison, Sofia says she adopts Celie's persona, simply doing what is asked of her and asking no questions.
The toil in prison is not Sofia's primary hardship. Being away from her children is the most difficult aspect of her sentence. Sofia correctly assumes that if she is made to serve her entire twelve year prison sentence, her youngest children will no longer remember who she is when she is released.
She despairs and seems on the brink of suicide or break-down.
Sofia's presence is huge from the very onset of the movie and the book. She is strong, and determined. Unlike many black women living in that era, Sofia refuses to be submissive to her husband Harpo, and the mayor. When he slaps her and she smacks him back, after refusing to work as a maid for his wife. Sofia is then attacked on the street by a mob of angry white men, and jailed.
While in jail she is beaten, and demeaned. She loses her strength and dignity when she is forced to work in the laundry while in jail, (without pay) and as a maid for the mayor's wife upon her release from prison. She is only allowed to see her children for short periods at a time.
It is clear that she has been broken when she is released from prison, and visits with her family. Her mental state is in a depressed mode until the place where she snickers at a remark about "white folk".
For me Sofia is a symbol of one being comfortable in their own skin, sure of themselves, and bendable but not breakable. In the end Harpo shows that he truly loves her. Her forgiving spirit even lends itself to Squeak, Harpo's mistress when Sofia helps Squeak to rear her children while seeking-after her singing career.
She may have been forced to be a laundress in prison and a maid but she was still Sofia, still a force to be reckoned with.
Hope this helps. Good luck in your high school career. Hope you plan to go on to college.
Sofia: "Sat in that jail, I sat in that jail til I near about done rot to death. I know what it like to wanna go somewhere and cain't. I know what it like to wanna sing... and have it beat out 'ya. I want to thank you, Miss Celie, fo everything you done for me. I 'members that day in the store with Miss Millie - I's feelin' real down. I's feelin' mighty bad. And when I seed you - I know'd there is a God. I know'd there is a God."