All text boxes on a webpage have boundaries, which are normally invisible unless the text box is selected. You can choose to show the boundaries of all your text boxes, which makes it easier to move or resize them.
Choose View > Show Layout (or Hide Layout).
These commands affect all pages in all your sites, not just the page that is showing when you choose the command.
The outlines of all the text boxes on the page appear as light gray lines; they don’t appear on your published website.