desa place, spot, region
bandhah combining, connecting, uniting, fixing
cittasya of mind, of consciousness
dharana the act of holding, keeping the mind collected, concentration
Fixing the consciousness on one point or region is concentration (dharana).
Commentary from Light on the Yoga Sutras by B.K.S. Iyengar
Dharana means focus of attention. Focusing the attention on a chosen point or area, within or outside the body, is concentration. By it the functions of the mind are controlled and brought to one focal point (sutra 1.2. yoga citta vritti nirodha or Yoga is the stilling the fluctuations of the mind).
Dharana, concentration, is where the mind directs its attention to any place, object, or idea of the practitioner’s choice. Many times during a meditation session the mind will quietly slither away, initially undetected (just as when you are in yoga class and the teacher sees that you are not paying attention). Each time the practitioner must let go of the wayward thoughts and refocus on the object of meditation. Over time, the mind wanders less frequently and becomes increasingly still, clear, and powerful.
The real purpose of yoga is often lost in the “doing” of the poses whereas concentration while doing, or meditation in action, to use a phrase that B.K.S. Iyengar often used, is essential to the practice of yoga.
Dharana is the art of reducing the interruptions of the mind and ultimately eliminating them completely, so that the knower and the known become one.
See more reading in Light on the Yoga Sutras by B.K.S. Iyengar