In plain words
Does such a person, fallen from both paths, perish like a cloud torn apart, unsupported, mighty-armed one, bewildered on the path to Brahman?
Word for word
Is it that, fallen from both, he does not perish like a torn cloud, without support, O mighty-armed one, bewildered on the path of Brahman?
The commentators
Bhagavadgītābhāṣyam· bhāṣya
कच्चित् किं न उभयविभ्रष्टः कर्ममार्गात् योगमार्गाच्च विभ्रष्टः सन् छिन्नाभ्रमिव नश्यति, किं वा न नश्यति अप्रतिष्ठो निराश्रयः हे महाबाहो विमूढः सन् ब्रह्मणः पथि ब्रह्मप्राप्तिमार्गे ॥ ३८ ॥
In plain words
"kaccit" — is that how it is? Does such a man, having slipped off both roads, off the path of works and off the path of yoga alike, come to nothing, the way a cloud torn loose comes to nothing? Or does he not come to nothing? "apratiṣṭhaḥ" means: with nothing under him, nothing to hold. O mighty-armed one — bewildered, and bewildered on the very path of Brahman, the road that leads to reaching Brahman.
Close to the Sanskrit
kaccit — is it that? — does he not, fallen away from both, that is, having fallen away from the path of works and from the path of yoga, perish like a severed cloud; or does he not perish? apratiṣṭhaḥ means without support. O mighty-armed one, being utterly bewildered on the path of Brahman, that is, on the road to the attainment of Brahman.