It means that life working a 9-5 job in an office cubicle, hence the term "cube" derived from cubicle.
A: Dude, my back hurts from sitting all day at work.

D: Yeah, that cube life.

Some Millennial: I'm not with that cube life. / I ain't about that cube life.

Senior undergrad: I'm not ready for that cube life yet. I want to travel and see the world.

A veteran (senior office worker) in that cube life: The cube life can be soul-crushing and soon you will just be zombies tip tapping on your keyboard.
by nomnombeast December 12, 2014
Get the cube life mug.