Features:

The image must have been taken in kind of a neutral density filter. So yours truly thinks it approximates what you would see if you just toned down the sunlight in the visible band (fiducial range 0.4--0.7 μm) to a tolerable level without re-mixing the colors. So the Sun looks yellow, but at a higher intensity would look like white light---or so yours truly thinks, but yours truly is NOT sure.?????
The background is fake.
Note the Sun is darker toward the edges where you are NOT seeing so directly into the hotter brighter deeper layers. You instead looking tangent through colder dimmer out layers.
The darkening toward the edge is called limb darkening.
The edge of an astro-body in projection onto the celestial sphere is called the astro-body's limb (astronomy).
In the image, we can see some sunspots. They look dark only by comparison to the rest of the Sun. They are a bit cooler, and so a bit dimmer than the rest of the Sun. They are a transient magnetic phenomenon---a part of solar activity (i.e., Sun weather) which is largely magnetic unlike Earth weather which is largely NOT magnetic. The aurora is key example Earth weather that is magnetic.
The key point about magnetic fields to remember at our level is that they cause the magnetic force on charged particles and this causes the charged particles helix along magnetic field lines. The helixing is because the magnetic force acts perpendicularly to the magnetic field lines AND the velocity of the charged particles with the sense of the perpendicularity set by the electromagnetic right-hand rule.
The Sun actually tends to look rather bland and quiescent in visible band (fiducial range 0.4--0.7 μm). In the ultraviolet and X-ray, the Sun looks more violent with big swirls---but, of course, the images from these wavelength bands are all in false color.