If you get black and blue marks easily, is that a sign of iron deficiency?

No. Usually new easy bruising in an otherwise healthy person involves either a low number of or dysfunctional platelets. This can be acquired (for example, immune-mediated thrombocytopenic purpura) or inherited. There are also inherited conditions that can affect the coagulation cascade (for example hemophilia) that can present with bruising. If concerned, see doctor.
Black and blue marks. Easy bruising is not really a sign of iron deficiency but of a bleeding issue. You should seek attention from your physician so that you can be examined and have appropriate blood testing ordered.