Voilà is a interjection like wow, ouch or eureka. It means look I have completed this or here it is. It calls attention to something new or just completed. As in, “You enclose the audio file in the RSS feed and Voilà… you have a podcast.” Sometimes the implication of voilà is this is the result of magic.
Since this is a actually a French word its etymology is just the translation from French- voi meaning “you see” and la meaning “there.” It can be spelled voila or voilà with an accent grave on the a.