Mrs. Hale is one of Carrie and Drouet's neighbors in their Chicago apartment. Mrs. Hale is obsessed with wealth and rich people (though she and her husband Mr. Hale are of modest means).
Spending time with Mrs. Hale stimulates Carrie's desire for wealth (for instance, they go and ogle rich people's houses). Check out the influence Mrs. Hale has on Carrie:
Not long after [Carrie] arrived Mrs. Hale established social relations with her, and together they went about. For a long time this was her only companionship, and the gossip of the manager's wife formed the medium through which she saw the world. (11.13)