This postcard consists of 55 colored rectangles arranged in an 11 by 5 grid. Since each year in someone's life is different, each rectangle is a different color. Also, every five years, I used a pattern rather than a solid color since some people consider ages ending in five or zero, such as 50, 55, and 60, to be significant!
Thanks Fleur, for the explanation (and for the beautiful card!). And does the little arrow in the green rectangle mean something as well?!
Yes, it's a north arrow. This card should be displayed with a vertical orientation.
So this is the right direction :-)