I don't know what kind of "diet" or program you are on, so I don't know the precise answer. However, off the top of my head I would say....
If you ate it as a fresh vegetable (usually known as "edamame") I would count it as a veg, if you ate it as a processed meat replacement (like if you bought some kind of soy based fake-meatball) I would count it as a meat.(though reluctantly--I would be tempted to call it a carb)
Does your program offer any info on beans as protein? Do they count a serving of any other beans as a meat? It may be best to count it as a veg since it doesn't have the fat content that "regular" meats do. (check the other ingredients: do they add any fat?)
Soybeans are a bean. Count it as the program says to count other types of beans. (kidney, pinto, black, navy) I would think a processed fake meat product like a fake "meat"ball would have a lot of other ingredients besides the soybeans though.
Gosh, after writing that out I think I would say you should count it as a veg, though you should take into account the other ingredients and maybe even call it a starch/carb. (many fake meats have wheat in them too)
What program are you on and what categories do they offer?