Literal translation
it's a phoenix!
Meaning
it's a wonder, something extraordinary
Explanation
An exclamation of admiring astonishment built on the implicit comparison with the phoenix, the mythical bird that rises again from its ashes. Calling something or some event un Fènis amounts to underlining its exceptional, almost miraculous character, something that escapes the expected order of things and inspires wonder, in the image of the fabulous bird that itself escapes death. The construction is transparent: the verb to be, the indefinite article, then the mythological proper noun capitalized. The register is that of admiring exclamation, used before a fortunate coincidence, an unexpected recovery, a success against all odds, or any event that seems to defy the ordinary course of things. The figure of the phoenix, borrowed from Greco-Roman mythology, has passed into popular southern culture as elsewhere in French, where c'est un phénix keeps a comparable meaning.