This is the section that says “Get your free shakeology sample!”
It can be used to display a call to action in the middle of the homepage.
The theme comes with two ribbon sections – BottomButton Ribbon & RightButton Ribbon. To customize them, navigate to Appearance > Customize > Ribbon sections, and fill in the blanks as necessary.
Each of the ribbons will only appear on your site when you have added some text to it.
You can change the colors in the ribbon using the Select Color buttons.
If you want to make the ribbon transparent, then drag the button highlighted above from 100 to 1 in the Background Color section.