In plain words
Take refuge in Him alone with your whole being, Bharata. By His grace you will attain supreme peace and the eternal abode.
Word for word
Go to Him alone as refuge with your whole being, O Bhārata; by His grace you will attain supreme peace, the eternal abode.
The commentators
Bhagavadgītābhāṣyam· bhāṣya
तमेव ईश्वरं शरणम् आश्रयं संसारार्तिहरणार्थं गच्छ आश्रय सर्वभावेन सर्वात्मना हे भारत । ततः तत्प्रसादात् ईश्वरानुग्रहात् परां प्रकृष्टां शान्तिम् उपरतिं स्थानं च मम विष्णोः परमं पदं प्राप्स्यसि शाश्वतं नित्यम् ॥ ६२ ॥
In plain words
Go to him alone — the Lord — as your refuge, your shelter, so that the pain of saṃsāra is carried away. Go, that is, take shelter, with all your being: with your whole self, Bhārata. Then — from that, meaning from his grace, from the Lord's favour — you will reach the highest peace, the coming to rest, and the abode that is mine, Viṣṇu's, the supreme state: everlasting, which is to say, without end.
Close to the Sanskrit
To him alone — to the Lord — as refuge, that is, as shelter, for the sake of removing the affliction of saṃsāra, go, that is, take shelter, with all your being, that is, with your whole self, O Bhārata. Then, that is, from his grace, from the Lord's favour, the supreme, that is, the pre-eminent, peace, that is, cessation, and the abode, mine, Viṣṇu's, the supreme state, you will attain — everlasting, that is, eternal.