CSS CSS Flexbox Layout Building a Layout with Flexbox Creating a Three Column Layout with Flexbox

Flexbox and a three column layout with extra space.

If a container is created for Flexbox with a three column layout inside and say the three columns are grouped close together, what happens to the space around those items/the space of the container? Would that space be no mans land so to speak? If another element say image is close to that container would it create weird behaviour?