Who is Anna from Nervous Conditions and what is their importance?

Anna is the woman hired by Babamukuru's family, who does the domestic chores for the household. When Nhamo dies, Anna stays several days with Tambu's family, and it's there that Anna and Tambu come to know each other. Tambu says that Anna chatters incessantly and when Tambu is not yet certain of the living arrangements at her uncle's house, Tambu believes she would be happy sharing a room with Anna, though the woman's chatter could disrupt her studies. Anna greets Tambu enthusiastically but as soon as Tambu's place in the household is sealed, including that she's to share a bedroom with Nyasha, Anna withdraws. Tambu says that she isn't certain she's ready to be someone Anna would kneel to but is cast into that role.