In plain words
We must join this head to God. To check the unsteadiness of the citta and make the citta one with Divinity: that is pratyāhāra.
Next, dhāraṇā. Dhāraṇā does not mean only looking at an object. Nor is it only concentrating on one subject. We must keep our gaze on our goal without wavering. For this power of dhāraṇā many great souls have practised many kinds of sādhana. Keeping some object in front of them and looking at that object in one and the same way: this is what they began with first of all. Ramaṇa Maharṣi used to sit on his rooftop at night, keep a single star in view, and hold his gaze on that star for many hours. This is the first path for developing dhāraṇā. In that way, having developed the power of dhāraṇā on one star, he gradually developed his object of meditation upon his own chosen deity. That is, the unwavering gaze. As long as this unwavering gaze is there, the wandering Manas stays under control. So dhāraṇā means the unwavering gaze. This is what we must develop. Gradually a Manas that does not wander will form in us.
Dhyāna means rising to the level of ‘I am Brahman’!
But on what are we to fix this unwandering Manas? That very thing, they said, is ‘dhyāna’. Dhyāna means nothing but the dissolving of Manas! What had to be merged in what, we have merged in it. Now there is no second thing. With Manas so merged, whatever object he sees, whatever persons he sees, whatever responsibilities he takes on, whatever duties he carries out, he holds firmly to the aim that none of these is he himself. In Vedānta they have described this as neti neti, not this, not this. I am not body, I am not mind. I am not the body. I am not Manas. I am not the Buddhi. I am not the citta. I am not the antaḥkaraṇa. I am not the senses. Then who are you? ‘Ahaṃ brahmāsmi.’ I myself am Brahman. To bring oneself to this state is the right dhyāna.