In this example, "Banner" is a type of card. Like other cards, it is configured with the layout template tool. From the properties I can see, the Banner card is set to full-width, and its Height is set to 5, which means that it will be 5 cells high in the 12-column grid. You can see that grey grid in your preview.
When you have a card selected in the layout template, you should see "Width" and "Height" boxes, and you should see a Full Width check box. It looks like your screen shot uses slightly older UI.
Two items match the rules of the Banner card, so they appear in your preview as full-width cards: "2062 Breakfast Blend" and another time that's not in view. (If you click "Mapping" you'll see the rules of each card type. I would guess that the "Banner" card has a rule that maps any banner item, but I'm not sure.)
You can read more about cards and layout (and watch a video) here: