Teta Elzbieta is Ona's stepmother. ("Teta" means aunt in Lithuanian, so her name is like Auntie Elzbieta in English.) Teta Elzbieta has six children of her own: Stanislovas, Kotrina, Vilimas, Nikolajus, Juozapas, and Kristoforas. These children all have various unhappy fates – check out their character analyses to discover what they are. The point is, Teta Elzbieta's primary role in the novel is to be the mother of the household. She looks after the cooking and cleaning until it becomes absolutely necessary for her to go out and get a job (after Marija and Jurgis become unemployed). She is also extremely, extremely practical. When Jurgis converts to socialism, Teta Elzbieta doesn't care at all. All she needs to know is that Jurgis's new socialist ideals mean that he is going to stand by her and help support her children once again; once she knows that, Teta Elzbieta goes with Jurgis to his Socialist Party meetings to show her support.
The flip side of Teta Elzbieta's maternal nature and strong practical side is that she is the most traditional member of the family. She insists on holding onto their Lithuanian social rituals even when doing so is kind of destructive in this new American context. For example, she absolutely insists that Ona and Jurgis hold a veselija, a proper wedding feast, even though spending the money practically bankrupts them. When her youngest child Kristoforas dies, Jurgis refuses to spend money on an expensive funeral (because they really, really can't afford it), so Teta Elzbieta goes begging to the neighbors to pay for a proper Mass and a special plot in the local graveyard.
Teta Elzbieta's insistence on tradition shows the generational difference between her and Jurgis. She is older and stuck in her ways, so she continues to react to America as though it is Lithuania. Jurgis, because he is young and flexible, is able to adapt and change according to America's demands on him. It's this flexibility that allows Jurgis to accept socialism in the end. Teta Elzbieta is a good person, but she also represents the more hidebound, traditional model of an immigrant worker. Because she is so conservative, Sinclair is pretty dismissive of Teta Elzbieta: he describes her condescendingly as, "a wonderfully wise little woman [... who] could think as quickly as a hunted rabbit" (30.1). As an idealist, it is not surprising that Sinclair despises Teta Elzbieta's pragmatic way of looking at everything, including the socialism that saves Jurgis's soul.
While Teta Elzbieta's fate is not as dire as Ona's or Marija's (e.g., she survives and becomes a beggar but not a prostitute), she still represents the vulnerability of women in Packingtown's rough-and-tumble world. As the oldest non-working member of the household early on in the novel, it is her responsibility to go to the housing agency and decide if they should go ahead and purchase their house. She is so unfamiliar with business matters that she doesn't know who to turn to to translate all the fine print of the deed. She signs the document and pays the family's down payment because she is intimidated by the real estate agent and his lawyer. Teta Elzbieta is isolated in the world of Packingtown, which leads to her making a disastrous financial decision that ruins the family once they miss their monthly house payments.