左 began as a drawing of a left hand. 工, a carpenter's square, was added later: the left hand holds the ruler while the right hand works. In ancient bronze inscriptions the hand alone meant both 'left' and 'to assist' — the helper hand.
Chinese honors sides differently by era: in the Zhou dynasty the left seat was the seat of honor for civil officials, while generals took the right. 左右 together means 'approximately' — because an estimate sits somewhere left or right of the true number.
A hand 𠂇 holding a carpenter's square 工 — your steady LEFT hand.
左右 zuǒyòu literally 'left-right' means 'roughly': 十个左右 = 'about ten'. You estimate by wobbling between sides.