tat-buddhayaḥ - those whose intellect is directed toward God
tat-ātmānaḥ - those whose heart (mind and intellect) is solely absorbed in God
tat-niṣhṭhāḥ - those whose intellect has firm faith in God
tat-parāyaṇāḥ - those who strive after God as the supreme goal and refuge
gachchhanti - go
apunaḥ-āvṛittim - not returning
jñāna - by knowledge
nirdhūta - dispelled
kalmaṣhāḥ - sins
Translation
Their intellect absorbed in That, their self being That, established in That, with That as their supreme goal, they go whence there is no return, their sins dispelled by knowledge.