The sign is a notorious one because the British did not allow Indian people in the club. They compared Indian people to dogs. To them Indian people are not better than the dogs.
Pritilata fought not only against the British rule but also against the gender discrimination because being a woman she received combat training and was assigned to lead a team. She did her assignment successfully. And to save her team and avoid arrest, she sacrificed her life committing suicide. It depicts her dual role.