休 is one of the loveliest compounds in the script: a person 亻 leaning against a tree 木. Three thousand years ago someone needed to write 'rest' and drew exactly what rest looks like on a hot day.
休息 is the everyday 'take a rest'; 休假 is vacation. Chinese work culture argues loudly about 休 — the right to 双休 (two-day weekends) was only standardized in 1995. The graceful old word 退休 'withdraw and rest' means retirement.
A person 亻 leaning on a tree 木 — pure REST.
午休, the sacred Chinese lunchtime nap, empties offices from noon to 1:30 — desks recline, lights dim, and disturbing a colleague's 午休 is a genuine faux pas.