In plain words
Seeing Your vast form with many mouths and eyes, mighty-armed One, with many arms, thighs and feet, many bellies and terrible fangs, the creatures of the world tremble—and so do I.
Word for word
Having seen Your great form of many mouths and eyes, O mighty-armed one, of many arms, thighs and feet, of many bellies, terrible with many fangs, the creatures [are] shaken, and so [am] I.
The commentators
Bhagavadgītābhāṣyam
यस्मात् —
रूपं महत् अतिप्रमाणं ते तव बहुवक्त्रनेत्रं बहूनि वक्त्राणि मुखानि नेत्राणि चक्षूंषि च यस्मिन् तत् रूपं बहुवक्त्रनेत्रम् , हे महाबाहो, बहुबाहूरुपादं बहवो बाहवः ऊरवः पादाश्च यस्मिन् रूपे तत् बहुबाहूरुपादम् , किञ्च, बहूदरं बहूनि उदराणि यस्मिन्निति बहूदरम् , बहुदंष्ट्राकरालं बह्वीभिः दंष्ट्राभिः करालं विकृतं तत् बहुदंष्ट्राकरालम् , दृष्ट्वा रूपम् ईदृशं लोकाः लौकिकाः प्राणिनः प्रव्यथिताः प्रचलिताः भयेन ; तथा अहमपि ॥ २३ ॥
In plain words
And why? Because —
Your form is vast — beyond anything I can measure — countless mouths, countless eyes, countless faces looking every way at once, O mighty-armed one. Countless arms, countless thighs, countless feet. Countless bellies too. And it is fearsome — row upon row of tusks, monstrous, terrible to behold. Seeing a form like this, every creature in this world trembles with fear. And so, I confess, do I.
Close to the Sanskrit
Because —
The form is great, exceeding all measure, your form, many-mouthed and many-eyed — many mouths, faces, eyes, organs of sight, and, in which form, that form is many-mouthed and many-eyed — O mighty-armed one; many-armed, many-thighed, many-footed — many arms, thighs, and feet, in which form, that is many-armed, many-thighed, many-footed; moreover, many-bellied — many bellies in which, thus many-bellied; fearsome with many tusks — fearsome, distorted, with many tusks, that is fearsome with many tusks. Having seen such a form, worldly beings, living creatures, are agitated, trembling, from fear; so am I too.