Juana is a strong woman who can withstand hardship, perhaps even better than Kino.

One example of Juana's strength is as follows;

Kino had wondered often at the iron in his patient, fragile wife. She, who was obedient and respectful and cheerful and patient, she could arch her back in child pain with hardly a cry. She could stand fatigue and hunger almost better than Kino himself. In the canoe she was like a strong man.