Your role is to go to the game and throw a ball at a YAK (FYI you are in the human/animal baseballympics)
a role. Use this about actors (役を演ずる： play a role!) Also used about businessmen who hold a certain post of position. That's right: post or position, not just role.
to be useful, to work like it's supposed to (used about things, not humans)
role, but more general and figurative than just 役（やく）。 Gay dudes who are top or bottom - that's 役割。 If your role is 'the black sheep of the family," that's 役割。 The guy in the boy-band who is "the edgy one." The person on the reality -tv show who is "the crazy one."
The verb is 果たす（はたす）, as in XXX の役割を果たす（ to play the role of XXX)
a petty bureaucrat ass-grower like at the DMV. These are almost as unpopular in Japan as they are in the West, so maybe don't ask someone "Are you a 役人?" to their face.
The pitcher's role is to THROW,
but if you gotta expand your sphincter's diameter, you gotta TAKE A DUMP .