In the novel, overalls are the standard clothing for all members of the Party, the ruling class of Oceania. They are described as "blue overalls with a red sash around the waist," reflecting the Party's colors. The fact that everyone wears the same type of clothing emphasizes the lack of individuality and the erasure of personal identity in this totalitarian society.
By requiring everyone to wear overalls, the Party aims to create a sense of uniformity and conformity among its members. It discourages any form of self-expression or differentiation through clothing choices. This uniformity is intended to promote the idea that everyone is equal and there is no need for individual style or preferences.
The overalls also serve as a reminder of the constant surveillance and control that the Party exerts over its citizens. The requirement to wear the same uniform makes it easier for the Party to monitor and identify individuals, discouraging any attempts at dissent or rebellion.
Overall, the overalls in "1984" symbolize the suppression of individuality, the control of the Party over its citizens, and the erasure of personal identity in the dystopian society of Oceania.