Global colors and global fonts are the colors and fonts you want to save on your website for convenience of use.
When you want to style an element, you see the global colors and fonts icon where you may click on them to use these pre-selected colors and fonts.
When you click on the global font icon, you can see the list of fonts you have preset in Global fonts. This works the same for Global colors.
To pre-save your Global fonts and Global colors, click on the hamburger icon on the top left corner of your editor panel.
Select Site Settings. The top 2 rows are your global fonts and global colors setting.
You can rename your colors or fonts to any name you like. You can change the original colors and fonts to your preferred ones, and even add new ones if necessary.