worldly-wise; skilled at navigating life; cosmopolitan
Describes a person who is adept at handling social situations, getting along in the world, and managing practical affairs smoothly. Often carries a positive nuance of savvy and adaptability.
He is worldly-wise and quickly fits into any workplace.
People who are skilled at navigating life know the tricks of human relationships well.
世渡り means 'making one's way in the world' or 'getting along in life'; 世渡り上手 adds 上手 (skillful) to describe a person who does this well.
社交的 focuses on sociability and enjoying interaction with others, while 世渡り上手 emphasizes practical wisdom and skill in handling life's challenges, not just socializing.
Compound of 世渡り (making one's way in the world) + 上手 (skillful). The exact historical derivation is uncertain, but the expression is transparently formed from its components.