it means "it is the life."
can also be trasnlated into english as:
- "that's life"
- "oh well, shit happens"
b: get over it! c'est la vie!
An associated idiom, "C'est la guerre", which means "This is war", would likewise best be interpreted as "Such is war.", inferring "This is just the way war is"
Person B: C'est la vie
A: Damn that bastard! I'll kill him.
B: So what about your car, c'est la vie. He's just a kid anyway...
A: NON! *eyes go red* C'est la guerre!
B: *shits pants*