Formal:
* Elle porte des boucles d'oreilles. (This is the most literal and formal translation.)
Informal:
* Elle a des boucles d'oreilles. (This is a more common and casual way to say it.)
* Elle a des piercings aux oreilles. (This specifically emphasizes that she has pierced ears.)
You can also say "she wears earrings" in French as:
* Elle porte des boucles d'oreilles. (This is similar to the formal translation, but emphasizes the action of wearing the earrings.)
The best choice will depend on the context of your conversation.