Complex sentence: According to Vedantic philosophy, Brahman in its highest form (nirguna) is without qualities, and therefore can only be understood through this process of negation which involves removing mental obstructions borne of ignorance that prevent the practitioner from realizing the true nature of Brahman.
Split into simpler sentences: According to Vedantic philosophy, Brahman in its highest form is nirguna (without qualities). Only through this process of negation which involves removing mental obstructions borne of ignorance can the practitioner realize the true nature of Brahman.