"Dhyana" is the penultimate of the 8 Limbs of Yoga and the next step in the path of meditation after "Dharana." "Dhyana" means "absorption" or "meditation" and it is meant to occur after you've been practicing Dharana, concentrating on a single object or focal point, for a time. The idea is that because of practicing this concentration you become completely absorbed.
When you become absorbed, the fluctuations of the mind cease, and boom! You are meditating!
See, we told you that so many of the 8 Limbs of Yoga are about meditation! It's a really important part of yoga. Next week we reach the end of this series and finally talk about the final stage of meditation and the final limb of yoga!