If one of Facebook's users (anywhere in the world) posts a piece of copyrighted material, and that material is served to a European user, then the copyright owner can take Facebook to court for copyright infringement under this legislation. I'm not even sure the owner has to be a European entity.
European law considers the offence to occur in the browser's country, not the server's country (hence Yahoo having to block all references to Nazi memorabilia as a result of a French court case held in France under French law despite Yahoo not being a French company).
Mind you, the US takes the same viewpoint, hence them suing to extradite Mr Dotcom from New Zealand for trial in the US for transgressing US law. The fact that he wasn't a US citizen, MegaUpload wasn't a US company, and he had committed no crime according to New Zealand law didn't matter. The US still considered his breach of copyright to have occurred on US soil, so he had committed a crime on US soil.
At least that's how I read it... I am not a lawyer.