बुद्धेर्भेदं धृतेश्चैव गुणतस्त्रिविधं श्रृणु। प्रोच्यमानमशेषेण पृथक्त्वेन धनञ्जय ॥

buddher bhedaṁ dhṛiteśh chaiva guṇatas tri-vidhaṁ śhṛiṇu prochyamānam aśheṣheṇa pṛithaktvena dhanañjaya

The division of Reason and of firmness also, threefold according to the qualities, hear thou related, unreservedly and severally, O Dhananjaya.

In plain words: Krishna tells Arjuna, whom he calls Dhananjaya (winner of wealth), that he will now explain the three kinds of reason (understanding) and of firmness (willpower).