In plain words
The all-pervading one takes on neither anyone’s sin nor merit. Jñāna is covered by ajñāna, and through this beings are deluded.
Word for word
The all-pervading one takes neither anyone's sin nor even merit; knowledge is covered by ignorance; by that beings are deluded.
The commentators
Bhagavadgītābhāṣyam
परमार्थतस्तु —
न आदत्ते न च गृह्णाति भक्तस्यापि कस्यचित् पापम् । न चैव आदत्ते सुकृतं भक्तैः प्रयुक्तं विभुः । किमर्थं तर्हि भक्तैः पूजादिलक्षणं यागदानहोमादिकं च सुकृतं प्रयुज्यते इत्याह — अज्ञानेन आवृतं ज्ञानं विवेकविज्ञानम् , तेन मुह्यन्ति ‘करोमि कारयामि भोक्ष्ये भोजयामि’ इत्येवं मोहं गच्छन्ति अविवेकिनः संसारिणो जन्तवः ॥ १५ ॥
In plain words
But in ultimate truth —
The Lord takes on no one's sin — not even a devotee's — and he takes on no one's merit either, no matter how much worship they offer him. So why, then, do devotees bother offering worship, sacrifice, charity, and oblations at all? Here's why: real knowledge, the discrimination that sees clearly, is covered over by ignorance, and it's this covering that deludes people — thinking, 'I act, I make others act, I will enjoy, I feed others' — undiscerning creatures caught in the round of birth and death fall into exactly this kind of confusion.
Close to the Sanskrit
But from the standpoint of the highest reality —
'Does not take on,' does not accept, the sin of anyone, even of a devotee; 'nor does' the all-pervading [Lord] 'take on' the merit performed and offered by devotees. Then for what purpose is merit, characterized as worship and the like, [namely] sacrifice, charity, oblation, and so on, offered by devotees? — to this he says: '[true] knowledge,' [i.e.] discriminative understanding, 'is covered by ignorance; by that they are deluded' — thinking, 'I do, I cause to be done, I shall enjoy, I feed [others]' — undiscerning, transmigrating creatures fall into delusion.