The Progress Dial tells you the following information:
The Card's scheduled completion date (here: June 2, 2015)
The Card's total points (18)
The portion of the Card you have completed so far (the colored arc. Here, about 20%)
Your pace. Your pace is calculated by Pract.us based on the number of points needed to finish by the completion date.
A pace example: if your enrolled in a 10 point Card due in 10 days, your average pace needed to finish on time is 1 point per day. As long as you meet that average pace, the dial color will remain green. As soon as drop below that pace, it will turn red (as shown above).
If you "catch up" by performing more Skills and earning more points, then your pace will change back to green. Also, if you extend your completion date, then pace color may change - a red Dial may turn green again just because more time was granted by your Manager..