The first occurrence
And God said, “Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years.” Gen 1:14
The primitive root
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 connection of “year” to “repeat” is that the cycles of the year repeat, year after year.