The most salient symbol in the novel is the book that the women work on. This book is uses the same phrase, "the help", as the novel-proper and some of its significance can be found in this phrase.
The term relates to both the attempt of alleviating the situation that the maids of Jackson face while also referring to the maids themselves. As a double entendre, the title helps to symbolize the novel's characters, their situation, their efforts to aid one antoher, and the ethos of the novel at large.
Celia's mimosa tree is another clear symbol in the novel. When she is prepared to be herself and stop trying to be accepted, she also stops accepting the presence of a tree in her yard that she dislikes. She chops down the tree with her own two hands, acting in a way that is true to her personal history and communicative of the changes that have taken place in her character to make her more assertive and self-assured.
The next day Miss Celia is sitting at the table and looking at the mimosa tree outside, the one she thinks is ugly and has wanted to get rid of for months. Minny wonders if she will still have a job after today. Miss Celia takes off her heels, cracks her knuckles, and heads outside into the rain. When Minny sees her next, Miss Celia is carrying an axe. She takes a practice swing and then she starts chopping. It is pouring rain and leaves are sticking to her, but every chop of the axe is stronger than the last. Minny sits at the table and waits for her to finish. (eNotes)