I'd have to know exactly what you are referencing here, such as is this what someone said or is this from a manufacturers web site or are these numbers that your pro shop gave you?????

But I'll give my best shot.

300/70 - the label on the particular arrow.
0.350 - the actual spine rating of the particular arrow
9.4 - the weight of the bare arrow shaft in grains per inch with nothing installed on or in the shaft.
433 - total finished weight of the arrow with vanes, inserts and tip installed.
278 - the speed of the finished arrow in feet per second.