Building tables in emails can help group pieces of information together, and the 'Row Group' feature can help with that. As shown below, it's the bottom option. In a nutshell, a Row Group is a container that holds Rows together (as many as needed). This means you can move around a whole section as you need, and the Rows don't need to be re-positioned individually.
The below screenshot illustrates how a Row Group looks, with a blue outline around the 3 Rows here. The handle on the right-hand side allows for dragging and re-positioning the rows all together.