Voir la vie en rose, literally “to see the life in pink”, means that you see the bright side of things, that you see life in a very optimistic way. The English equivalent is “to look at life through rose-tinted glasses”.
It appeared in the 18th century when pink was the symbol of happiness. Does this expression remind you of something? Maybe yes, maybe no. But “La vie en rose” is one of Edith Piaf’s most popular songs!