In your hand it does nothing at all
Every ability on every card is written "the owning company." Mail contracts pay the company. Coal mines, bridges, the Steel Mill — all company powers. A private sitting in your play area produces nothing, ever, until you put it inside a railroad.
In 18RoyalGorgePrivates pay you every OR from the moment you win them, and selling one to a company is how you take profit. Here there's no income phase and no resale — only deployment.