Sabo's mother, whose name has not been revealed, is a noble from the Goa Kingdom. She and her unnamed husband adopted Stelly as a secondary heir and son.
She exhibits the typical personality of a noble, primarily concerned with elevating her family's status. This was evident when her son got into a fight with a noble boy of higher status who used a weapon against him. Instead of tending to her own son's injuries, she apologized to the other family while comforting their son, completely disregarding her child's well-being.
(Source: One Piece Wikia)
