At best, a picture might give voice / "speak" to a simple phrase or a very short sentence. iMo, that is why the lunatic academic fringe picture making crowd always finds it necessary to have lengthy and often obtuse artspeak bullock as companion to their pictures. When it comes to picture making, they are trying their best to cram 2 lbs. of crap into a 1 oz. bottle.
What that crowd seems to not grasp is the fact that a picture is first and foremost a form of expression which appeals to the visual senses. And, in appealing to those sensibilities, a picture can be about "nothing", referent wise, yet still be a very good picture indeed.
Independent of the depicted referent, a very good / outstanding picture can be "about" light, shape, form, color and the resultant organization of space created by the picture maker's framing. Such a picture is invariably a visual delight to a viewer's visual sensibilities and, in the absolute best examples, is also capable of instigating a pricking of a viewer's thought process which is dominated by their personal experience and knowledge, not by what the picture maker is trying to "say".