…and that picture is not it.
Actually, this is an image of Barnard 68, a dark interstellar cloud made up of dust and molecular gas, absorbing light.
The void this text is referring to is the Eridanus Supervoid, distant and apparently empty (though there are alternative explanations). The only way it’s been detected is by an apparent cold spot in the cosmic microwave background radiation.
That vaguely pointy looking shape is a vast expanse of space, half a billion light years across which, seemingly, contains absolutely nothing. This isn’t empty the way space around us is empty – the interstellar space in our galaxy is full of gas, dust, ions, plasma… all sorts of things (including clouds like Barnard 68 up there). This? This is a void. A big, inexplicable, vacuous expanse which should not be there.
It’s like a hole in the Universe.