A French cuff shirt is a dress shirt with French cuffs also called double cuffs.
French cuffs are folded back and are fastened with cufflinks or silk knots.
In the past most dress shirts were with French cuffs.
Today, French cuff shirts are considered as fashion shirts, and are often worn with eveningwear.
French cuff shirts are considered to be more formal than button cuffs.
Nevertheless, French cuff shirts are not really suitable for some professionnal events as job interview. A button cuff shirt is better, more unobtrusive, for these kind of events.