Primarily, magpie symbolic meanings deal with expression. This is due to the wide range and variability of her vocalizations. Her song, which is more like an other-worldly chatter is a unique and specialized communication in the animal world. Her voice has often been said to communicate messages from the spirit realm.
To further this point, in the west, the magpie is associated with witchcraft and wizardry. Lore often depicts the magpie among witches, and there are claims that this bird (along with the crow) commonly serves as a familiar (spirit embodied in the form of an animal) to the witch.
This legend was likely started due to the complex vocalizations of the bird, as there are also other stories that the magpie was said to speak spells to witches and wizards.
The magpie persists in the lore of witches and wizards due to her insatiable attraction to all things shiny. Just like the crow (of which the magpie shares the same family in the animal kingdom) the magpie will go out of her way to get a closer look at a shiny, sparkly bauble, and will often steal the trinket. Lore further states the magpie taking these baubles back to her master (typically a witch or wizard).
For more information on magpie symbolism, visit my Magpie Symbolic Meanings webpage.