tada (तदा, tadā) = (adv.) then
viveka (विवेक, viveka) = (iic.) discernment; power of discernment
nimnam (निम्नम्, nimnam) = (acc. sg. m./acc. sg. n./nom. sg. n. from nimna (निम्न, nimna)) incline towards
kaivalya (कैवल्य, kaivalya) = (iic.) liberation
prak (प्राक्, prāk) = (nom. sg. n. from prach (प्राच्, prāc)) orientation; inclination
bharam (भारम्, bhāram) = (acc. sg. m. from bhara (भार, bhāra)) weight
chittam (चित्तम्, cittam) = (acc. sg. m./acc. sg. n./nom. sg. n. from chitta (चित्त, citta)) spirit; mind; understanding

Discernment is the key to liberation

Discernment (viveka (विवेक, viveka)) is the key to changing the unity of the physical, energy, emotional and mental domains (chitta (चित्त, citta)) in such a way that they lead directly to the path of liberation (kaivalya (कैवल्य, kaivalya)).

viveka (विवेक, viveka) and avidya (अविद्या, avidyā) as opposites

Discernment (viveka (विवेक, viveka)) is the exact opposite of a lack of insight (avidya (अविद्या, avidyā)) and thus of all other burdens on the spiritual path (klesha (क्लेश, kleśa)) that we encountered in chapter 2 of the Yoga Sutra. We recognize the difference between our true nature (drashtu (द्रष्टु, draṣṭu)) and the unity of the physical, energy, emotional and mental domains (chitta (चित्त, citta)) (asmita (अस्मिता, asmitā)); we realize that our fortunes and sufferings are not dependent on outer circumstances (raga (राग, rāga), dvesha (द्वेष, dveṣa)); and we lose our deep seated anxiety (abhinivesha (अभिनिवेश, abhiniveśa)). Thus kaivalya (कैवल्य, kaivalya) is ultimately liberation from a lack of insight (avidya (अविद्या, avidyā)) and the other burdens engendered thereby (klesha (क्लेश, kleśa)). However, in the next sentence Patanjali (पतञ्जलि, Patañjali) not only tells us what what we should free ourselves from, but also provides a worthwhile goal.