To interchange two things is to trade or switch them. If the painting hanging on your wall just doesn't fit the room, you can interchange it with the photograph on the opposite wall.
When you're baking a pie, you can usually interchange one kind of fruit for another, or interchange tapioca for cornstarch to thicken the filling. When interchange is a noun, it has various meanings including "highway intersection," or the place where these busy roads meet each other. This road meaning dates only from the 1940s, while the "change places" meaning is at least 400 years old.