The Settings tab/options allows you to set Bootstrap Grid classes to control the column width on different devices. Setting 12 equals 100% width. Setting 6 equals 50% width, etc. Note that if you set, for example, 50% on tablet, it will inherit this width for larger screens as well unless you set otherwise - so you don't need to set the width for all devices/breakpoints if you want the same width to apply to the larger devices as well.
I only discovered the role of the Settings option today, as I had been trying to add the classes manually, but Pagebuilder was removing them. If you're not familiar with Bootstrap Grid, there is a whole page dedicated to it on their website that explain the rules (but I'm guessing you already know it).
