"Yo le hablo a la mesera en francés."
Translation:I speak to the waitress in French.
Apparently, there are several Spanish verbs that require a redundant indirect object pronoun even when the indirect object is also in the sentence. I'm still looking for a complete list but verbs of communication like hablar and decir are included.
Hablar and decir commonly use an indirect object pronoun, but these verbs do not require one.