We first encounter this attractive courtesan upon Siddhartha's arrival in the city of child-people; she is the "queen" of the Hindu art of love. Then, as life in the city becomes transparently illusory for her, as it did for Siddhartha, she seems to realize that love cannot be dispensed secondhand, as an art form.
There is a subtle pause in the role of Kamala in the plot after we follow Siddhartha out of the city, but it is strongly hinted that she will reappear later as a changed person. She emerges finally as a Buddhist and we learn that she transcended the "art" of love by directly experiencing it with Siddhartha. Her being carried off from this world in Vasudeva's hunt bears symbolic significance to her transformation.