In French, we say "viens à 21 heures," or "come at 21 hours," quite literally. Yes, "hours" is a duration as one poster commented; and yes, also in French. But

In French, we say "viens à 21 heures," or "come at 21 hours," quite literally. Yes, "hours" is a duration as one poster commented; and yes, also in French. But the context gives the meaning away.