Sitting quietly, doing nothing
and the grass grows by itself
That is the proposition.
The japanese word for just sitting is shikantaza.
It is used in the context of Zen Buddhism.
The term 'Zen' derives from the chinese 'Chan', which in turn has its root in the sanskrit 'Dhyana', a term describing the sitting practice central to Zen Buddhism.
Meditating is not connected to any religion whatsoever.
It means different things to different people, and the motives as of why to meditate vary.
There surely are benefits that derive from sitting in meditation.
But first and foremost it offers the possibility to become aware of your natural state.