Pratyahara means literally control of ahara, or gaining mastery over external influences.
Pranayama means discipline of energy. Control of the breath.
Asanas means sitting postures. We use asana physical postures to sit for long periods in meditation.
Niyamas means positive duties
Yamas means right action or living
Dharana means concentration
Dhyana means one point focus. Concentration + Meditation.
Samadhi means the highest state of mental concentration that a person can achieve while still bound to the body and which unites them with the highest reality.