He means that we should show respect for others, and treat them as we would like to be treated ourselves.

As I understand it, Kant mean that in any action, all persons involved must be recipients of the good. You should not use a person as a means of achieving the good for another unless that first person in someway benefits.
This is sometimes used in critiquing utilitatian ethics.
If 51 % of the people could live a wonderful existence if the other 49% were enslaved, would that be ethical?
Kant would say that the 49% would also have to benefit from the right action, so the above question would not be morally justified.

Thank you so much for your post. It really helped me have a better understanding. I am studying Business Ethics this semester and it has been hard for me to understand some of this.

Thanks again.

Thank you for replying, but why can't the text book just say that? It would be a lot easier to understand. Thanks again, it makes more sense to me now.