Bell-mère was Nami and Nojiko’s adoptive mother, seen in a flashback during the Arlong Park Arc.
That same day Arlong invaded the island and found her home, Bell-mère tried to fend them off but was quickly subdued. When asked for the fee needed to stay alive, it turned out all the money Bell-mère had would either save herself or her two daughters. Things likely would have been okay if she had followed Genzo’s advice and paid for herself, as Arlong was unaware of their existence.
However, Bell-mère declared the money was for her daughters, as she would rather die than not call herself a mother. To that end, Arlong shot her right in front of the eyes of her two adopted daughters, but not before Bell-mère apologized to Nami for not being richer, and not being able to buy the girls whatever they wanted, but the two insisted that it was not the case and urged her to stay alive. Before she died, she told the girls, “I love you.”