Ayuda con articulo del garbage collector

Hola amigos alguien mepuede explicar esto?
Take out the trash
While the garbage collector is an excellent feature of the .NET Framework,
it often needs help to determine when an object is ready for garbage
collection. You can provide help by calling the Dispose method whenever it
is available on objects as soon as possible. On the same note, you should
not reference objects once they are no longer needed. The reason is the
garbage collector will not process them if they are referenced



Gracias

Saludos

Cesar