When you view the row settings in mobile view, you will come across a feature that allows you to “disable vertically stacking rows on mobile devices”.

When you select (tick the box) this option, the system will NOT auto stack rows vertically. In most cases, you want to enable this feature (which means you leave the checkbox unchecked). Unlike the desktop view, the mobile viewing area is smaller, therefore systeme io, by default, will automatically stack the rows together when users view on mobile devices.
For example, this website has a row with 2-column. This is what it looks like on desktop view:

When switching to mobile view, this is how it appears by default:

The above is with vertically stacking rows featured enabled (by default). Notice how the left column (the women’s image) and the right column (the text) are vertically stacked.
If you checked the box (disable vertically stacking rows), here’s what it looks like in the mobile version:

It may appear okay in the screenshot above, but when viewing in the mobile screen, the whole appearance doesn’t look very good.
So, the rule of thumb is always to leave this box unchecked unless you are sure it looks better and proper without stacking the rows.