間に合う
まにあう · maniau · JLPT N4 · verb-godan
to be in time for
⏰🚆 間に合う = interval (間) + in (に) + fit/meet (合う): to fit in the gap
間 (ma) is a gap of time, に marks where, and 合う (au) means to fit or meet. So ma-ni-au is literally fitting into the time gap: you arrive while the window is still open, i.e. you are in time for it.
合 — 乛 (lid/roof) + 口 (mouth)
Originally a pictograph of a lidded vessel — a cover (亼) closing over an opening (口) — giving the core sense of 'come together, join, fit.' From 'fit/match' it extended to 'combine, unite, agree' and to measure-word uses. The reading hé reflects this 'joining' meaning.