～代
～だい · ～dai · JLPT N4 · noun
age
📅 sounds like DIE: each age must die for the next one to begin
代 = person (亻) + a marker of replacing: one generation stepping in for another. As a suffix, ～代 labels a span: 20代 = one's twenties, 90年代 = the nineties, 時代 = era.
代 — person radical 亻 + 弋 (stake/dart, phonetic)
代 is a semantic-phonetic compound: 亻 (person) gives the meaning and 弋 supplies the sound. The original sense was one person taking the place of another, which broadened to 'substitute,' 'replace,' and then 'generation' or 'era' — successive groups of people replacing the previous.