If you are interested in technical working of PCV system, you can search about it. Some info about breather is give below.
In order for the PCV system to sweep fumes out of the crankcase, the crankcase must have a source of fresh air. The source of this fresh air is the "crankcase breather", which is usually ducted from the engine's intake manifold. The breather is usually provided with baffles and filters to prevent oil mist and vapour from fouling the air filter.