The 'Big 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. There is an icon selection included in the element, and the icon is presented in a larger format than in the 'Icon, Text and Button' element. The element can be found below 'Content elements' when creating a new element. (1.3.1)
In the 'General' tab you can see that the content element type 'Big icon, Text and Link' is selected.
The element uses the regular header field (1), text field (2), button text field (3) and area for a link (4). (1.3.2)
Note: it is not possible to format text (2) with row breaks, linked text or any type of text transformation, this is just a plain text field.
In additional setting (1.3.3) you can disable whole area link (5), show button as a link (6) and select an icon by clicking on it (7).