अर्जुन
In plain words
Arjuna said: Lord, by what marks is one known who has transcended these three guṇas? How does such a person live, and how does one go beyond the three guṇas?
Word for word
By what marks is one who has passed beyond these three guṇas [known], O Lord? Of what conduct [is he]? And how does he go beyond these three guṇas?
कैर्लिङ्गैस्त्रीन् गुणानेतानतीतो भवति प्रभोकिमाचारः कथं चैतांस्त्रीन् गुणानतिवर्तते
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
जीवन्नेव गुणान् अतीत्य अमृतम् अश्नुते इति प्रश्नबीजं प्रतिलभ्य, अर्जुन उवाच —
कैः लिङ्गैः चिह्नैः त्रीन् एतान् व्याख्यातान् गुणान् अतीतः अतिक्रान्तः भवति प्रभो, किमाचारः कः अस्य आचारः इति किमाचारः कथं केन च प्रकारेण एतान् त्रीन् गुणान् अतिवर्तते अतीत्य वर्तते ॥ २१ ॥
In plain words
From those words — that while still alive a person crosses beyond the guṇas and attains the deathless — Arjuna took the seed of a question, and spoke:
By what signs, Lord, can we recognize someone who has truly gone beyond these three guṇas you've just explained? 'What is his conduct?' simply means: what does he do, how does he behave? And more than that: in exactly what way does he step past these three guṇas and go on living?
Close to the Sanskrit
Having received the seed of a question, namely "while living itself, having transcended the guṇas, one attains the immortal," Arjuna said —
By what marks, indicators, does one who has transcended, gone beyond, these three guṇas already explained, become, O Lord? 'Of what conduct' [means]: what is his conduct — thus 'of what conduct'; how, by what manner does he go beyond — transcend, proceed — with respect to these three guṇas?