बुद्ध्या विशुद्धया युक्तो धृत्याऽऽत्मानं नियम्य च। शब्दादीन् विषयांस्त्यक्त्वा रागद्वेषौ व्युदस्य च ॥

buddhyā viśhuddhayā yukto dhṛityātmānaṁ niyamya cha śhabdādīn viṣhayāns tyaktvā rāga-dveṣhau vyudasya cha

United to this Reason, purified, controlling the self by firmness, having abandoned sound and the other objects of the senses, having laid aside passion and malice,

In plain words: Krishna begins describing the person ready for the Eternal. They have a clear, pure mind and steady self-control. They turn away from sense pleasures like sounds, and they drop strong likes and dislikes.