"les" + singular proper noun
For example, what does
mean? "Johns"? In the sense of: "People like Jean"?
Sometimes you can find this kind of construction. For instance, "Les Baptiste" will mean "All people named Baptiste". The proper noun can also refer to a entire familly like "les Dupond" (without additional "s").
In French, family names don't take an s in the plural, so I'd guess that this refers to "the Jean family." Some additional context would help, though. :)