The pubic piercing is a unisex surface piercing through the skin of the pubic mound.
As with almost all surface piercings, this one will eventually migrate itself out of the skin. However, proper care (and not yanking on it all the time) will drastically increase the amount of time you get to share with your pubic piercing. Also similar to most surface piercings, a special type of barbell called a surface bar (looks like a [ or an overgrown staple with threaded ends) must be worn in this piercing, lest the piercing reject in just a few days. Oftentimes a surface bar will be custom bent just before the piercing is done, so the jewerly is an appropriate size for the new piercing.
Folks usually get this piercing because they want metal through something down there, but not necessarily through the sensitive bits. For those who have a habit of showing off piercings to anyone who asks, the pubic is a good one because it doesn't require full frontal exposure to show it to someone you just pull down the front of your pants a little.
As with all piercings, and especially genital piercings, go to a professional if you want one done. Even though the piercing isn't right near any large blood vessels or nerves, surface piercings are a much different beast than other piercings and aren't an easy thing to do right the first time. That said, make sure you find a piercer who's done pubic piercings before playing the guinea pig to a piercing is only slightly better than playing the guinea pig for a tattoo artist.