You start with mainly a team of non-specialized workers, but during the game you can hire additional ones with specific skill sets. The cost or effect of an action is determined by the type of worker that does it.
To complete your company objectives, you will have to remove some of your workers from your active pool, promoting them to managerial positions.
You must carefully assign each of your workers to perform the right action at the right time in order to exploit their specializations in the best way.
You also then need to decide when to promote them, because once you do, you can no longer use them to take actions.