If you enable this icon 
on the ribbon tab Home | group Paragraph, you can show formatting markers, such as paragraph marks, tabs, spaces, etc., so that they are easier to recognize in the text.
To hide the formatting marks, click on the icon again.
Note: You can also show non-printable characters in a differentiated manner via the ribbon command File | Options, View tab by selecting only individual characters there. For more information, see Settings, View tab.