संन्यासस्य महाबाहो तत्त्वमिच्छामि वेदितुम्। त्यागस्य च हृषीकेश पृथक्केशिनिषूदन ॥

sannyāsasya mahā-bāho tattvam ichchhāmi veditum tyāgasya cha hṛiṣhīkeśha pṛithak keśhi-niṣhūdana

I desire, O mighty-armed, to know severally the essence of renunciation, O Hrishîkesha, and of relinquishment, O Keshinishûdana.

In plain words: Arjuna asks Krishna to explain clearly the difference between renunciation (giving up actions) and relinquishment (letting go of the results of actions). He uses Krishna's titles, Hrishikesha (lord of the senses) and Keshinishudana (slayer of the demon Keshi).