Meditation means concentrated thinking.  Yoga-meditation is a method of directing the concentrated thinking towards pure consciousness.

In yoga-meditation we calm our mind, withdraw it from the external world, concentrate it inwardly and direct it towards the unlimited consciousness within. We do that with the help of a mantra. A mantra is a sound, which when meditated upon, frees the mind from its limitations, such as negative thoughts, fear, greed, anger and selfishness. The mantra has two main qualities, the sound and the meaning. The sound calms and harmonizes the mind. By ideating on the meaning of the mantra, the mind becomes subtle and free from limiting thoughts. It becomes absorbed in the object of one's meditation, which is pure consciousness. As you think, so you become. When you deeply think about the infinite, blissful self within, with full attention and heart, you will experience it and eventually your mind will fully merge in it. You are then at one with your blissful self.