In plain words
speaking, releasing, grasping, opening and closing the eyes—knowing that the senses alone move among their objects.
Word for word
speaking, releasing, grasping, opening and even closing [the eyes], holding firmly [in mind] 'the senses move among the objects of the senses'.
The commentators
Bhagavadgītābhāṣyam
नैव किञ्चित् करोमीति युक्तः समाहितः सन् मन्येत चिन्तयेत् , तत्त्ववित् आत्मनो याथात्म्यं तत्त्वं वेत्तीति तत्त्ववित् परमार्थदर्शीत्यर्थः ॥
कदा कथं वा तत्त्वमवधारयन् मन्येत इति, उच्यते — पश्यन्निति । मन्येत इति पूर्वेण सम्बन्धः । यस्य एवं तत्त्वविदः सर्वकार्यकरणचेष्टासु कर्मसु अकर्मैव, पश्यतः सम्यग्दर्शिनः तस्य सर्वकर्मसंन्यासे एव अधिकारः, कर्मणः अभावदर्शनात् । न हि मृगतृष्णिकायाम् उदकबुद्ध्या पानाय प्रवृत्तः उदकाभावज्ञानेऽपि तत्रैव पानप्रयोजनाय प्रवर्तते ॥ ९ ॥
In plain words
'I am not doing anything at all' — that is what he should hold, and keep holding, while yukta, that is, gathered and settled. And tattvavit: he knows the self as it actually is, he knows the tattva — that is what makes him a knower of truth. One who sees what is ultimately real: that is the sense.
When, or how, does someone come to think this way, having grasped the truth? The answer is: by seeing. That word 'seeing' is what connects back to the earlier line. Someone who knows the truth like this sees only non-action in every activity of every instrument and organ — in all action itself. For someone who sees, who sees truly, the only thing left to be eligible for is renunciation of all action, because he sees straight through to the absence of any real doer. It's like someone who set out to drink from what looked like water in a mirage — once he knows there's no water there, he doesn't go on trying to drink from it anyway.
Close to the Sanskrit
'I do not do anything at all' — thus, being yukta, that is, composed, he should think, should reflect. Tattvavit: he knows the true nature of the self, the reality — thus, tattvavit; one who sees the ultimate reality, that is the meaning.
'When, or how, ascertaining the truth, should he think [this]?' — it is answered: 'seeing' [is the answer]. 'Should think' — this word connects with the earlier [word, 'seeing']. For one who, thus knowing the truth, [perceives] only non-action itself in all the activities of the instruments and their effects, [i.e.] in actions — for that one who sees, who sees rightly, the eligibility is only for renunciation of all action, since he sees the absence of action [as agent]. For one who has set out to drink from a mirage through the notion of water, does not, even upon coming to know the absence of water there, proceed there for the purpose of drinking.