I'm now an A level student, but I did 'Of Mice and Men' for my GCSEs so I'm happy to help. The question is asking how the author creates the character of Curley's wife, how she/our opinion of her changes throughout the book, and how important she is to the book/why she is there. If I were writing this essay, I would include the following points:
1) Look at the first time we meet Curley's wife; what language does Steinbeck use to describe her? (eg she thrusts forwards seductively, suggesting that she's aware that she's attractive and likes having men's attention
2) How do the other men talk about her? (eg Lennie's interest in her and George's warning is foreshadowing of the tragic end of the book) also, the fact that she is simply refered to as "Curley's wife" shows how she has no real status or identity as an individual (possibly because she's a woman)
3) How much power does she have (eg Curley bullies her, but she bullies Crooks at the end of chapter 4)
4) Colour/aminal symbolism; what kinds of things is she compared to? What does this tell us about her personality/character?
5) How does she seem when she talks to Lennie in the penultimate chapter? Is she naive for believing that she could have been a star? Or is she a tragic symbol of the failure of the American Dream?
6) Her death: how is it described and what significance does it have?
Conclusion: Why is she an important character, what does she represent and does she change at all through the book?
Good luck; how long is the coursework meant to be?
Like Plumstone said really. From what I remember he introduces her off the bat as someone who is beautiful and knows it but is also manipulative because she is lonely. Just ask 'what point do she serve to the book'?
The fact she doesn't have a name is also significant. She's just always referred to as "Curly's Wife"; the only other character who doesn't have a name is the dog. It shows that Curly's wife is seen as a possession, and a (sexual) object. The men basically see her as on par with the dog.