Something is adding the <i class="fa about "></i>
before the text. The weird thing is that it doesn’t look standard so it may be easy to remove.
Log into WordPress and go to Appearance -> Menus then find the menu that it’s in. You may have to change the dropdown at the top left to find the right menu. Once you’ve found the correct menu, on the right-side expand the “About” and remove all that text, backspace until there’s nothing there. Then Replace it with the original text “About”. Finally, save the menu. Hopefully that solves it.
If not it may be a theme or plugin related issue. At that point it may be wise to either reach out to your local WordPress community ( via a meetup or something similar ) and see if anyone there would lend their time to solve the issue.
Another option is to keep digging yourself by installing the WP Healthcheck Plugin. This will help you disable all the plugins and possible revert back to the default theme. If you disable all the plugins and the menu re-aligns then you know it’s one of the plugins causing the issue. If you revert to the default theme and your menu re-aligns then it’s a theme issue and you may be able to contact the theme developers to maybe push out a patch for the issue.