In plain words
Knowing these two paths, Partha, no yogin is deluded. Therefore be collected in yoga at all times, Arjuna.
Word for word
Knowing these two paths, O son of Pṛthā, no yogin at all is deluded; therefore at all times be collected in yoga, O Arjuna.
The commentators
Bhagavadgītābhāṣyam· bhāṣya
न एते यथोक्ते सृती मार्गौ पार्थ जानन् संसाराय एका, अन्या मोक्षाय इति, योगी न मुह्यति कश्चन कश्चिदपि । तस्मात् सर्वेषु कालेषु योगयुक्तः समाहितो भव अर्जुन ॥ २७ ॥
In plain words
These two — sṛtī here means simply the two paths, the ones just described. O Pārtha, the yogin who knows them knows this: one path leads back into saṃsāra, the other leads to mokṣa. Knowing that, he is not deluded. Kaścana means any yogin at all — not one of them loses his way. So at all times be yoked to yoga, be gathered and collected, Arjuna.
Close to the Sanskrit
These two — sṛtī, that is, the two paths, as described — O Pārtha, knowing them: one is for saṃsāra, the other for mokṣa — thus knowing, the yogin is not deluded, kaścana, that is, not any one of them at all. Therefore, at all times be yogayukta, that is, collected, O Arjuna.