On the Statistics tab in the dialog box of the ribbon command File | Properties 
, you can retrieve statistical information about the current document (number of characters, number of sentences, average word length, etc.).
Tip: If you select a section of text before you choose this function, it will show statistics for the selected text only; otherwise, it will show them for the entire document.
The items of information are mostly self-explanatory. Only the difference between the first two options needs to be explained:
▪Characters counts the visible characters only.
▪Keystrokes also counts all white spaces (space bar, tab key).
Thus, the sentence "This is a test" has 14 characters or 17 keystrokes (because it contains three spaces).
Tip: Add buttons for "Statistics" to the status bar/ribbon tab
If you need the above statistics functions regularly, you can add corresponding buttons to the status bar or to any ribbon tab to ensure that this information is permanently displayed on the screen.
To do so, choose the ribbon command File | Customize 
| Customize ribbon and select the entry Statistics in the Categories section (top left) in the open dialog box.
In the Customize section (top right), then select the entry "Status bar" or the ribbon tab on which you would like to place the button. Now, add the desired button from the list Commands on the left: Count keystrokes, Count characters, Count words, etc.
For more information on customizing the ribbon buttons, see Customizing the ribbon.