Translation:Stephanus goes to the market with Corinna.
If the pronunciation in the audio recordings for this course were better, you should also hear a difference in the pronunciation of Corinna. In Stephanus et Corinna, in the nominative case, the a on the end of Corinna would be short; in the phrase Stephanus cum Corinna, Corinna is in the ablative case and the a in the ending should be long.
This is the definitive book on the subject (can't say I've read it yet). It pulls evidence from classical sources to reconstruct the sounds of classical pronunciation. There are (apparently) a fair amount of surviving texts that discuss grammar and pronunciation of the language.