Bomb ; The name of the shell thats going to be created. In this case its pointless and can be left off , unless you want to later move the shell around.
"Heat125" and "Shell125" ; The types of object being created. In this case, a sabot round, and a heat round.
(Getpos plane) ; Where the objects are being created, in this case they are being created at the position of a object named "plane", one would assume the code is designed to destroy a plane.