私用
しよう · shiyou · JLPT N3 · noun
use
🔑 私用 = private (私) + use (用): something just for you
私 means private or I, and 用 means use or errand. Together they mean personal use, or a private matter, e.g. leaving work on 私用. Its reading しよう is the same as しよう, the 'let's do it' form, so the kanji tell you which one is meant.
用 — pictograph of a bucket or wooden pail
用 originally depicted a bucket or container, possibly a sacrificial vessel made of wood. Over time it was borrowed to mean 'to use' or 'employ,' losing its concrete object sense. The modern meaning 'use' has been standard since early classical Chinese.