StudioPress themes are built on the Genesis Framework and several of these themes have a flexible grid built into the home page layout.
The layout grid on the site’s front page changes depending on how many widgets you place in each widget area.
This section of the site explains how these flexible layout grids work
Flexible layouts are NOT built into all themes. But if your theme has them, they’re really useful.
The diagram below gives you a good idea of how the layout changes depending on how many widgets are placed in a front page widget area.
To learn about Flexible Layouts