助手
じょしゅ · joshu · JLPT N3 · noun
assistant
🤝 助手 = help (助) + hand (手): a helping hand
助 means to help, as in 助ける (tasukeru). 手 means hand, and in compounds it often marks a person who does a job, as in 歌手 (singer) or 選手 (athlete). So a 助手 is literally a help-hand: the person who assists.
手 — pictograph of a hand with five fingers
手 is a pictograph showing an open hand with fingers and a wrist. Early bronze and oracle bone forms clearly depict five splayed fingers, which simplified over time into the modern shape. It keeps its original meaning of 'hand' and also serves as a radical in many characters related to hand actions.