"C'est la vie" = 'that's life" or "such is life" is an expression you can use when , for example, you lost a football game, you're disappointed, and you say "we lost,, that's life after all". In French," on a perdu (we lost ), c'est la vie après tout !
It's about a situation which happens and you can't do anything about it.
hope this time I helped !!