What does où travaille le professeur mean?

"Where does she work?" is an English equivalent of the French phrase Où est-ce qu'elle travaille?

Specifically, the preposition où is "where". The verb est means "(it) is" in this context. The masculine demonstrative pronoun ce means "it, that, this". The conjunction que* means "that". The personal pronoun elle means "she". The verb travaille means "does work, is working, works."

The pronunciation will be "oo eh-skehl trah-veye" in French.

*The vowel e drops -- and is replaced by an apostrophe -- before a Word which begins with a vowel.

The sound is similar to that in the English noun "eye".