What does 'DirectX error' mean in the context of CS:GO fatal errors, and how can I fix it?

A 'DirectX error' indicates a problem with the DirectX runtime environment, which is essential for running games. To fix this, try updating DirectX. While Windows Updates usually handle this, you can download the DirectX End-User Runtime Web Installer from Microsoft's website. If that doesn't work, reinstalling DirectX can be attempted, although this is less common nowadays.