अथवा बहुनैतेन किं ज्ञातेन तवार्जुन। विष्टभ्याहमिदं कृत्स्नमेकांशेन स्थितो जगत् ॥

atha vā bahunaitena kiṁ jñātena tavārjuna viṣhṭabhyāham idaṁ kṛitsnam ekānśhena sthito jagat

But what is the knowledge of all these details to thee, O Arjuna? Having pervaded this whole universe with one fragment of Myself, I remain.

In plain words: Krishna tells Arjuna he does not need all these details. It is enough to know that Krishna holds up the whole universe with just one small part of himself, and still remains beyond it.