Prose
S. B. U. II. 20
In plain words
This entry is not Sanskrit at all — it is a stray citation label from the printed page, 'S. B. U. II. 20', almost certainly a marginal cross-reference to another section of the text, picked up here by an extraction artifact rather than being part of the commentary itself.
Close to the Sanskrit
[Not a sentence of the commentary: a bare page/section citation marker, 'S. B. U. II. 20', carried into the record as a print-extraction artifact rather than continuous bhāṣya text. It most likely abbreviates a cross-reference such as 'Bṛhadāraṇyaka Upaniṣad, section II.20'.]