You may want to create a website page but not publish it on your website. Why would you want to do that?
Go to Menus>Menu Manager and create a new menu called eg 'Dummy Menu' and save it.
Go to Menus>Dummy Menu and create a link by clicking on 'New' in the top right, choose type 'Article' and link it to the page you want to use. If you click on 'Apply' instead of 'Save' when you're finished, you'll see the 'Link' field change as below.

Copy the value in the 'Link' field, you'll need this. Append this value to your website address, eg our address is www.dotcomkiosk.com so in this example we'll need to add the link value to the end by copy and pasting it. Note the forward slash between the website address and the field value (in red below):
www.dotcomkiosk.com/index.php?option=com_content&view=article&id=558
Use the link you just created and send it to the person you wish to show it to, or use it to preview your page without publishing it. This link is also known as the 'Non-SEF URL'. Nobody else will be able to see the page, because the steps above explain how to create an independent link, which is not shown anywhere on your website.
Either click Close or Save to exit out of the menu item you just created.