Hi there -
Are you referring to an app? It sounds as if you are referring to the My Cycles app, but if you aren't, let us know.
On the app, the pink shaded lines mean days that your period is predicted to happen. The green lines indicate a higher chance of fertility, and the green gets darker as you get closer to ovulation, meaning the better of a chance you'll have of getting pregnant. This allows you to either plan when you'll try to get pregnant, or avoid pregnancy, whichever you are trying to do.
The days with no colors mean you aren't likely to have your period or get pregnant. Please remember that this is only an app, and not a guarantee.
I hope this helps, but let us know if you need further assistance. Any time you need assistance with an app, you can tap on App Support in the menu on the left side and send us an email.
Emily
Colors for what? I have no idea what you're asking. Sorry