Rows and columns are containers for your content components which help you structure your page. You can't add content directly onto the page, you must drop a content component into a container.
If you select a pre-populated template screen, e.g. two column, text and image, accordion… then there will already be rows and columns set up for you. But, feel free to add more or take some out to suit the layout of your learning content.
Columns are always added within row, which means you can have a row with one column and then still add a row with two columns below it on the same page, giving you a flexible layout.
Standard rows have automatic padding at either end so your learner isn't reading text which goes right to the edge of the page.
Full width rows will always span the whole screen (with no padding), so these are ideal for image banners. You can still split this up into columns if you wish by adding columns within the row.