In my member list, there is a colored circle with a number. What does this mean?

The number indicates the amount of days in which the member has not come to the club. The color that appears refers to a type of risk: red identifies high risk, yellow medium risk, green low risk and grey no risk (recently entered the club). 

You can change the number of days that identify risks by going to the "Club" menu, clicking on "Information" from the drop down menu and then clicking on the "Configuration" tab.

Scroll down you will see the fields to change the number of days related to each risk.