旬 means 'season'

The sun, moon, and seasons are natural clocks, but time is also a construct. As this bundle shows, the Japanese divide time into units of 10 (days, months, or years), also perceiving 72 microseasons. Japan has observed lunar, solar, and other calendars, plus 60-year cycles and multiple era systems. For all this precision, people approximate time with "the good old days," "once upon a time," or "around the time." They also have a particular take on time when saying that a food is in season, "at your age," and "It's a great time" for a certain activity.