It’s a phoneto-semantic compound: the 少 stands for the sound “miao” and the 禾 points back to the original meaning of the word: awn of grain
秒：禾芒也。从禾少聲
Image credit: Fir0002/Flagstaffotos
The choice of 少 (shao) as a phonetic for /miao/ may seem odd at first, but note that the same choice was made for 妙、眇、渺、杪. There are some old Chinese gymnastics about complex initials that you can go through on wiktionary if you want to know more on why
少 - Wiktionary
* Parentheses "()" indicate uncertain presence; * Square brackets "[]" indicate uncertain identity, e.g. *[t] as coda may in fact be *-t or *-p; * Angle brackets "<>" indicate infix; * Hyphen "-" indicates morpheme boundary; * Period "." indicates syllable boundary.
https://en.m.wiktionary.org/wiki/少#Chinese
But, in any case, if you’re interested in Chinese character etymology, remembering that 少 can stand for /miao/ is useful.
The\ meaning\ “second”\ \(as\ in\ time\)\ is\ a\ much\ later\ development\ of\ the\ sense\ of\ the\ word\.
source:\ Quora