FYI, you seem to be new here and seem not to be far-left. For your future enjoyment of lemmy, note that Lemmy.ML is a communist instance and therefore you may not like some of the content there.

Lac Léman, is the french word for what english people call lake geneva (all the region around lac léman is french speaking).

Léman comes from celtic “lemann” which means lake.

So lac léman is the lake lake. Given it is the biggest lake in western europe, not a bad name.