A font is a graphical representation of text that may include a different typeface, point size, weight, color, or design.
The Untrusted Font Blocking security feature provides a global setting to prevent programs from loading untrusted fonts. Untrusted fonts are any font installed outside of the C:\Windows\Fonts directory. This feature can be configured to be in 3 modes: On, Off, and Audit.
After you turn this feature on, or start using Audit mode, you can look at your event logs for details.
This tutorial will show you how to view the event logs in Event Viewer for details about Untrusted Font Blocking in Windows 10.