Row have same function like section. Row will give you a separate wrapper for a content block inside.
Row can be made for full width or with container (standard). You can edit your row like yourself for how many column you want. You just need to click edit row after you create a row.
you can also add a margin or padding into your main row (section) at the right side panel of the row option.
If you add a background and want it to be a cover of your content you should choice the "background image display" as cover and add the row class "parallax". It automatically will change as parallax image background.