dharanasu (धारणासु, dhāraṇāsu) = (loc. pl. f.) for dharana; concentration; harmony with thoughts; harmony in the mental body; the sixth of the eight steps.
cha (च, ca) = (conj.) and
yogyatah (योग्यताः, yogyatāḥ) = (acc. pl. f./nom. pl.) fitness; preparedness; qualification; capability
manasah (मनसः, manasaḥ) = (g. sg. n./abl. sg. n./acc. pl. m./nom. pl. m./g. sg. m./abl. sg. m. from manas (मनस्, manas)) mind

Dharanaa (धारणाअ, Dhāraṇāa)

The sentence above actually occurs earlier, since the ashtanga yoga pratyahara (प्रत्याहार, pratyāhāra) technique that follows here is described one sentence later.

Dharana (धारणा, Dhāraṇā) means concentration. The next step is a natural outgrowth of the previous ones. The harmony that was previously attained with the physical body, energy and emotion now becomes the goal for gaining control over one’s thoughts.

To experience how difficult this is to achieve, do the following brief exercise: While sitting in a comfortable position for a few minutes with your eyes closed, try not to think of a blue elephant with bells around its neck. You will probably find, as do most people, that this is an impossible task, i.e. you will inevitably think about the elephant.

According to the ashta“nga yoga (अष्टा“न्ग योग, aṣṭā“nga yoga) tradition, the key to Dharana (धारणा, Dhāraṇā) lies in the aasana vinyasa (आअसनविन्यास, āasana-vinyāsa) system. The transition to this step occurs all by itself, thus allowing you to increasingly focus your attention on your practice, which will in turn be imbued with increasing awareness.

Here too, ashta“nga yoga (अष्टा“न्ग योग, aṣṭā“nga yoga) offers a number of other techniques that can be practiced in addition to the asana vinyasa (आसनविन्यास, āsana-vinyāsa) system.