When you want to take a print of a page you have to adjust the area of a particular page so that your content will remain on it.
With Google Docs ruler you can easily adjust margins on both left and right sides of a page. You can also use ruler to indent in Google Docs. So the ruler in Google Docs is very important.
How to show ruler in Google Docs
Open Google Docs on your computer
In the “Menu bar” click on the “View” option then navigate and click to “Show Ruler” you will get a display horizontal ruler on the top and a vertical ruler on the left side of the Google Docs document editor.
How to show vertical ruler in Google Docs
When you enable the option “Show Ruler” in the docs, you will see a vertical ruler on the left side of the outline in Google Docs.
You can use the ruler on Google Docs to control the height of the page, take your mouse cursor to the left vertical ruler until the arrow becomes a double-sided arrow.
Then hold and drag the double side arrow up or down to adjust the length of the content of a page.
Similarly, use the ruler to adjust the width of the page take the mouse cursor to the top horizontal ruler, and when the arrow becomes double side adjust the content width of the page.
The above image is a reference to how to show ruler in Google Docs and control it for adjusting left margin, right margin, and top margin.