There are 3 possible dimensions that can be possible for any object. They are the length, width and height. Any object seen by us can only possibly have these 3 dimensions. So there is no such 4th dimension that can be clearly explained. So what we see in our eyes is a 3D image. However, some researchers explain that if a 3D object is in motion, it can be considered to be in 4D. Though it may not be a very logical explanation, but presently that motion of objects in 3D is the only avaliable explanation for a fourth dimension.