In plain words
You are the Father of this moving and unmoving world, its most venerable Guru, worthy of worship. None is equal to You; how then could there be another greater than You in the three worlds, incomparable in power?
Word for word
You are the father of the world, of the moving and the unmoving; You [are] its worshipful one and its weightier teacher; there is none equal to You: whence another greater, even in the three worlds, O You of matchless power?
पिताऽसि लोकस्य चराचरस्यत्वमस्य पूज्यश्च गुरुर्गरीयान्न त्वत्समोऽस्त्यभ्यधिकः कुतोऽन्योलोकत्रयेऽप्यप्रतिमप्रभाव
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
यतः त्वम् —
पिता असि जनयिता असि लोकस्य प्राणिजातस्य चराचरस्य स्थावरजङ्गमस्य । न केवलं त्वम् अस्य जगतः पिता, पूज्यश्च पूजार्हः, यतः गुरुः गरीयान् गुरुतरः । कस्मात् गुरुतरः त्वम् इति आह — न त्वत्समः त्वत्तुल्यः अस्ति । न हि ईश्वरद्वयं सम्भवति, अनेकेश्वरत्वे व्यवहारानुपपत्तेः । त्वत्सम एव तावत् अन्यः न सम्भवति ; कुतः एव अन्यः अभ्यधिकः स्यात् लोकत्रयेऽपि सर्वस्मिन् ? अप्रतिमप्रभाव प्रतिमीयते यया सा प्रतिमा, न विद्यते प्रतिमा यस्य तव प्रभावस्य सः त्वम् अप्रतिमप्रभावः, हे अप्रतिमप्रभाव निरतिशयप्रभाव इत्यर्थः ॥ ४३ ॥
In plain words
Because you —
You are the father — the one who brought it all into being — of this whole world, every living thing in it, everything that moves and everything that doesn't. And you are not only its father: you deserve to be worshipped, because you are guru, weightier than anything, more venerable than any teacher could be. Why more venerable than the rest? Because, Śaṅkara says, there is simply no one equal to you, no one comparable to you at all. There cannot be two Supreme Lords — if lordship were divided among many, the ordinary workings of the world we live in simply wouldn't hold together. Even a mere equal to you isn't possible, to begin with — so how, in all three worlds, could anyone possibly surpass you? And that word the verse gives you, 'unmatched power' — a match is whatever something gets measured against, and nothing exists that could be measured against your power. That is exactly who you are: power with nothing to compare it to, power beyond every rival.
Close to the Sanskrit
Since you —
You are the father, you are the begetter, of the world, of the mass of living beings, moving and unmoving, of the stationary and the mobile. Not only are you the father of this world, but worthy of worship, deserving of worship, since [you are] guru, weightier, more venerable. Why more venerable [than others]? He states — there is no one equal to you, comparable to you. For indeed a duality of Lords is not possible, because in a state of multiple lordship, the [ordinary] transactions [of the world] would be incoherent. To begin with, even a mere equal to you is not possible; how then could another be superior, in the three worlds, in their entirety? [As for] 'one of unmatched power' — that by which something is matched is called a 'pratimā'; there exists no pratimā of your power — that is you, one whose power has no counterpart, O one of unmatched power, meaning: one of unsurpassed power — that is the meaning.