The 'Icon, Text and Button' element is an info box, that is often used on the start page or as a promo box in a right hand column on subpages.
You can find the element below the tab Content elements when creating a new element. (1.4.1)
In the 'General' tab you can see the content element type 'Icon, Text and Button' selected.
The element uses the regular header field (1) and a text field (2), which is a plain text field, and it is not possible to format this text with row breaks, linked text or any type of text transformation. (1.4.2)
Moving on, you can set a link text (4), link address (5), set if only the button should be linked or the whole info box (6), if the button should be a text link instead of button (7) and finally select an icon by clicking on it (8). (1.4.3)