The Spacer Card should be used when you want to add space between different elements on a page.
In this example there is very little space between the headline and the image:
If we add a spacer between the headline and the image we can increase that space:
The spacer will be highlighted when you hover over the area between the headline and the image:
Spacer Card Menu
The blue Text Card menu appears when you click on a spacer within the page:
You can control the height of the spacer by clicking and dragging the slider shown below. Drag to the left to decrease the height of the spacer. Drag to the right to increase the height of the spacer: