। ॥
In plain words
"The world is real" — that is how it appears, and for a mind not yet ripened that appearance is exactly what keeps it circling through birth and death. So the Upaniṣads say it plainly: all of this, every bit of it, is unreal.
Close to the Sanskrit
The notion 'the world is real' would lead to saṃsāra for those whose minds are unripe; therefore the Upaniṣads establish that all this is unreal.