To answer this question, we need to travel a lot. Literally. Since we are in the twenty first century it is safe to say that the brilliant minds from all around the world have made deductions from the data that they have procured to answer the above question.
The Galactic centre is a good distance away from where we stand, to be precise, 26000 light years away. But this did not stop the curiosity of mankind from probing into the possibility of visualising the centre of our galaxy.
It shouldn’t be new knowledge that we belong to the Milky Way galaxy. And hence the galactic centre we are talking about pertains to the same. The centre of our galaxy encompasses stars, dust, gas and a gigantesque black hole known as Sagittarius A* that has a mass of around four million suns. It is only possible to visualise the galactic centre through powerful telescopes that detects variety of light forms such as X-ray and infrared light which includes Chandra X-ray Observatory and other telescopes.
As stated earlier, the galactic centre possess stars amongst which are Wolf-Rayet stars which are hot luminous stars that are rapidly losing mass in a wind. Powerful winds of gas streaming from the surface of these stars are carrying some of their outer layers into interstellar space.When the outflowing gas collides with previously ejected gas from other stars, the collisions produce shock waves, similar to sonic booms, which percolate into the surrounding area.These shock waves heat the gas to millions of degrees, which causes it to glow in X-rays. The images we see of the galactic centre is basically the stars , the heated up gas due to collision and dust. The black hole is invisible to the human eye because of the large amount of dust present in the surroundings. Speaking of this monstrous black hole which takes in anything in its vicinity, the galactic centre could be home to thousands of tiny black holes which are too small to be studied.
Scientists are of the belief that Sagittarius A* is what is at the exact centre of our galaxy, hidden within the bar core. Bar core is home to about 10 million stars which together forms a glow area.
These stars move at a speed of about 1000 km per second, thus proving the existence of a black hole. If not for a super massive black hole, these stars would be moving at a slower pace.
To conclude, the centre of our galaxy is all stars, dust and a humongous black hole which to the human eye may look like blobs of glitter sand on a black paper.