अर्जुन
In plain words
Arjuna said: Keshava, what marks a person of steady wisdom, established in samādhi? How does one of steady understanding speak, sit, and move?
Word for word
What is the mark of one of steady wisdom, established in samādhi, O Keśava? How would one of steady understanding speak, how sit, how move?
The commentators
Bhagavadgītābhāṣyam
प्रश्नबीजं प्रतिलभ्य अर्जुन उवाच लब्धसमाधिप्रज्ञस्य लक्षणबुभुत्सया —
स्थिता प्रतिष्ठिता ‘अहमस्मि परं ब्रह्म’ इति प्रज्ञा यस्य सः स्थितप्रज्ञः तस्य स्थितप्रज्ञस्य का भाषा किं भाषणं वचनं कथमसौ परैर्भाष्यते समाधिस्थस्य समाधौ स्थितस्य हे केशव । स्थितधीः स्थितप्रज्ञः स्वयं वा किं प्रभाषेत । किम् आसीत व्रजेत किम् आसनं व्रजनं वा तस्य कथमित्यर्थः । स्थितप्रज्ञस्य लक्षणमनेन श्लोकेन पृच्छ्यते ॥ ५४ ॥
In plain words
Given the seed of a question, Arjuna spoke — wanting to know the marks of someone whose wisdom has been won in samādhi —
'Steady' here means firmly, permanently established — someone whose wisdom, 'I am the supreme Brahman,' has become fixed. That is who is meant by 'one of steady wisdom.' Now, Arjuna asks: How does such a person speak? What are his words like? How would others, Keśava, describe someone who is established, settled, in that deep absorption? Or, put differently: how would he himself speak? How would he sit, how would he walk — what do his stillness and his movement look like? That is really what Arjuna is asking. This entire verse is simply Arjuna's question about the defining marks of someone of steady wisdom.
Close to the Sanskrit
Having received the seed of a question, Arjuna spoke, out of the desire to know the marks of one who has attained the wisdom of samādhi —
'Steadied,' well-established — one whose wisdom, 'I am the supreme Brahman,' is fixed, he is 'one of steady wisdom.' Of him, of that one of steady wisdom, 'what is his speech' — what is his speaking, his utterance; how is that one, situated in samādhi, established in samādhi, described by others, O Keśava? [Or:] would the one of steady mind, the one of steady wisdom, himself speak, or what would he say? What would he sit [like], what would he move [like] — what is his sitting, his moving, or how [are these] for him: such is the meaning. The characteristic marks of the one of steady wisdom are asked by this verse. [End of commentary on verse 54.]