Two piercings just
under the bottom lip: one on the left side and one on the right. They can be studs or rings, or even a combination of both.
They are called
snake bites as a snakes fangs
puncture two holes next to each other, ie. the two holes through the skin under the lip next to each other.
Snake bites used to mean two piercings next to each other anywhere on the body, but are now more recognised as the lip type as these seem to be the most popular.