![Screenshot](file:///C:/Users/steve1969/Pictures/Screenshots/Screenshot%20(7).png)
I can’t see your screenshot, but I think you mean something like this:
If it is, it’s called “Word Completion”. If the word is what you intend to type, just hit Enter and it will appear in full.
You can tinker with this feature at Tools > AutoCorrect Options… > Word Completion.
Tip: You can use Ctrl-Tab to cycle through other long words you’ve type with the same beginning.