In plain words
Know tamas, born of ajñāna, to delude all embodied beings; it binds through negligence, laziness, and sleep, Bharata.
Word for word
But know tamas [to be] born of ajñāna, deluding all embodied beings; it binds by negligence, indolence and sleep, O Bhārata.
तमस्त्वज्ञानजं विद्धि मोहनं सर्वदेहिनाम्प्रमादालस्यनिद्राभिस्तन्निबध्नाति भारत
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam· bhāṣya
तमः तृतीयः गुणः अज्ञानजम् अज्ञानात् जातम् अज्ञानजं विद्धि मोहनं मोहकरम् अविवेककरं सर्वदेहिनां सर्वेषां देहवताम् । प्रमादालस्यनिद्राभिः प्रमादश्च आलस्यं च निद्रा च प्रमादालस्यनिद्राः ताभिः प्रमादालस्यनिद्राभिः तत् तमः निबध्नाति भारत ॥ ८ ॥
In plain words
Tamas is the third of the three strands. "Born of ignorance" — that is, arising out of ignorance: know tamas as ignorance's own child. "Deluding" — meaning it manufactures delusion, it destroys your power to tell the real from the unreal. And it does this to "all the embodied" — to everyone who wears a body, no exceptions. "By heedlessness, indolence and sleep" — heedlessness, and indolence, and sleep: those three together make up the word; and it is by those three, by inattention, by sloth, by sleep, that tamas ties you down, Arjuna.
Close to the Sanskrit
Tamas — the third guṇa. Ajñānajam: born from ignorance; know tamas to be born of ignorance, deluding — that is, delusion-producing, non-discrimination-producing — of all the embodied, that is, of all those possessing bodies. Pramādālasyanidrābhiḥ: heedlessness, and indolence, and sleep — these are 'heedlessness-indolence-sleep'; by those, that is, by heedlessness, indolence and sleep, that tamas binds, O Bhārata.