Light can’t escape beyond the event horizon - the sphere surrounding the black hole where the gravitational attraction is so strong that the escape velocity exceeds the speed of light. Black holes emit ion jets that are visible in different wavelengths and outside of the event horizon there are gas and dust clouds that glow. What this picture demonstrates is a passing star losing mass to the black hole - think of it as a whirlpool injecting star matter as it passes.
There’s typically an accretion disk of stuff not yet fallen in, in a tight orbit around black holes, which are orbiting at extremely high speeds and with very different speeds at different heights, leading to extreme frictional heating and temperatures in the accretion disk. That’s what’s depicted here.