Emacs sometimes displays clickable buttons (or other informative icons), and you can customize how these look on display. The main customization point here is the icon-preference user option. By using this, you can tell Emacs your overall preferences for icons. This is a list of icon types, and the first icon type that's supported will be used. The supported types are:

image

Use an image for the icon.

emoji

Use a colorful emoji for the icon.

symbol

Use a monochrome symbol for the icon.

text

Use a simple text for the icon.

In addition, each individual icon can be customized with M-x customize-icon, and themes can further alter the looks of the icons. To get a quick description of an icon, use the M-x describe-icon command.