sheniy, “second,” strong’s H8145

The first occurrence.

And God called the firmament Heaven. And the evening and the morning were the second day. Gen 1:8

The primitive root.

Strong’s H8145, sheniy, an adjective meaning, “second;” the ordinal of two; from Strong’s H8138 שנה shanah, a primitive root meaning, “to repeat.” The 3-letter root is shin + nun + hey.

shin  ש = two front teeth, thus sharp, press, eat, two, again
nun נ ן = the seed, thus continue, heir, son
hey ה = man with upraised arms, thus look, reveal, wonder, worship, breath

The story: Something happened once, and now a second (shin) time, so that it continues (nun) to be evident (hey, in the sense of being pointed out).

THE ANCIENT HEBREW LEXICON | INDEX OF HEBREW ROOTS