it doesn't matter if we've heard of it. Of course, yes, I've heard of it. But there was NO CLUE that we were supposed to be using a French phrase/song title. And really, there are many--most--Americans and others who know no French whatsoever. And most people under age 50 have never heard of Edith Piaf. I'm over 50, so I have. But this sentence definitely does not belong in this course!
It means "life in pink" or "the life in pink" just as "Cuộc sống màu hồng" does. As far as metaphorical meaning, it's like life through pink lenses being a life of bliss or ecstasy. I assumed the question was what does it mean as in what is the phrase a reference to because there seemed to be confusion about why a French phrase was the translation instead of English and it's a big part of early-20th century pop culture.