The modern day 21st century ultimate show of force/projection of power on sea is the aircraft carrier, but back in the 1940s the battleship served that role (the concept of a carrier strike group was still in its infancy in WWII). The "joke" is that if the overhead satellite shot of the 003 carrier were taken in the 1940s, one might think the PLA were building a battleship instead, which is why it has red markings to illustrate what a hypothetical battleship might look like with cannons and what not.