Enabling Twig debugging involves locating thetwig.config[debug]settings in your services.yml file and changing their values.

These variables can be edited either directly in sites/default/services.yml, or alternately they can be added to the sites/development.services.yml file if you followed the steps above to use a settings.local.php file.

Take a look at this video:

This is what each of those settings is used for:

debug: (boolean) Enable various debugging features in the Twig engine.

auto_reload : (boolean) When set to `true`, Twig will automatically recompile all templates when their source code changes.

cache : (boolean) Disabling the Twig cache by setting this to `false` will recompile the templates from source each time they are used. In most cases the `auto_reload` setting above should be enabled rather than disabling the Twig cache.