Perhaps the most widely known cakra is Ajna, the 'Third Eye'. The nature and function of Ajna could summarized as accurate perception. Typical, day-to-day knowing is accomplished by perceiving through the five senses and analyzing by the rational mind. We 'know' a thing by comparing it to a preconceived, or already known, example of the general category to which that thing exists.
For example, typically when we see a tree, we take in just enough visual information about the tree to know that it belongs to the general category of "tree"; we, then, label it a tree and move one. In this way, the world around us, our understanding, or knowing, of the world around us consists almost entirely of approximations. We do not really know that tree, because we dd not really look at it.
How much of the world around you have you really investigated? Do you look people in the eye and truly listen when they talk, or do you simply take in bits and pieces of what they, mostly those pieces that correspond most closely to things and ideas you already know? When was the last time you truly saw something, for what it, itself, is and not for what it is similar to or for the generic category to which it belong Most likely, when this happened, you found yourself - you - almost lost in the experience....
Such an experience could be considered transcending the basic duality of life - the duality of you, as a separate entity, and everything else. This transcendence, or merging, of duality, effected through accurate perception, is the function of Ajna.
It is associated with the mind, but not the analyzing mind discussed above, or the always insecure 'drunken monkey' mind, forever questioning and undermining knowledge. It is that inherent ability to know directly - without comparison and logical analysis - the nature of things. (This sounds odd - how can we know a thing without analyzing it? Remember, however, Ajna is the transcendent mind, the mind that lost itself in complete awareness of another. It is the merging of dualities, after which it is realized there are no things that are not also self - intimate knowledge is, then, simply self-awareness, or even more simply just Awareness.)
The practice of yoga being an infinitely practical one, all of the above is utterly void of value without actual, personal experience. Such experience is quite easily practiced with Ajna. All one has to do is practice being witness to the events of your life. With pleasurable situations, notice yourself enjoying them. With painful ones, observe how you respond, witness the suffering. It as if you were stepping out of the forest, witnessing the forest, in order to know it better.