The Chinese idiom "小事一桩" is formed by combining the character 小 (small) with 事 (matter) to create the compound 小事 (minor matter), which is then followed by 一 (one) and 桩 (a measure word for events or tasks, originally meaning "stake"). This structure literally translates to "one stake of a small matter", using 一桩 as a quantifying phrase to emphasize the singular, trivial nature of the issue, thus figuratively representing something insignificant or easily resolved.