Nothing too special, just a clock that counts in balanced ternary. Green is +1, yellow is 0, red is -1. The dark grey is just for padding purposes, treat them as leading zeroes. Most significant trit is the left-most trit. Numbers kept track of are as follows:
If it was a simple ternary clock - it would be easier but the balancing ternary makes it a little more confusing
I think it easiest to start with the day - which is green yellow which is 1 0 which is 1 x 3 + 0 == 3
Then try decoding the month but remembering that a red negates the second digit so instead of it being 1 x 3, its -1 x 3 so green red green which is 1 -1 1 which is (1 x 9) + (-1 x 3) + 1 == 7