In traditional Chinese culture, family lineage is of paramount importance, and a clear distinction is always made between the paternal and maternal sides. The father's side is considered the “inner family” (本家, běnjiā), while the mother's side is the “outer family” (外家, wàijiā). The term 舅舅 is a direct reflection of this worldview.
Comparison with “Uncle”: An English speaker uses “uncle” for their father's brother, mother's brother, and even their aunt's husband. This single word masks the specific relationship. In Chinese, this would be highly ambiguous. A 舅舅 (jiùjiu) holds a distinct role as the primary male figure from your mother's original family. He is culturally different from a 叔叔 (shūshu) (father's younger brother) or 伯伯 (bóbo) (father's older brother).
Family Role: The 舅舅 often plays a special and respected role in a child's life. He can be seen as a loving authority figure from outside the immediate paternal line, sometimes acting as a mediator or a source of support. In some regions, the 舅舅 holds a place of honor at family events, especially his nephew's or niece's wedding. This respect underscores the importance of maintaining strong ties with the mother's family.