Fraxure is a new dragon type pokemon in Pokemon Black and White. Fraxure evolves from an Axew at level 38, and evolves into Haxorus at level 48.
Fraxure can only be caught on the outer Victory Road, and will be level 40 when you encounter it.
Alternatively you can catch an Axew in Mistralton Cave and it will evolve into Fraxure at level 38.