If you copy and paste text from somewhere else (like an email or webpage), you may discover that it does not always appear exactly as you would expect. If you use the Paste as text button, a special cleanup process will run to remove any special formatting and HTML tags that may otherwise change your text.
From the visual editor, click on the Toolbar Toggle button:
This will open more toolbar options where you’ll find the Paste as text button:
A pop-up box lets you know it is now safe to paste in pre-formatted text. Press the Paste as text button again to stop the feature.