Texture 1. Albedo (diffuse)
Texture 2. Roughness map
Texture 3. Normal map
Texture 4. Probably a mask for something, not sure.
Texture 5. Most likely a mask for skin imperfections
Texture 6. Mask for Hair Particles
In order toto make a human face, the 3 first maps are really the only once you need.
To make a proper albedo map you will likely have to use scanned textures, and project them on to the face and do the cleanup afterwards.
if you dont quite understand how this works, go watch a video of someone texturing a face using this technique, preferly a sped up video. not a tutorial.
Then you use a roughness map to define where the character is more glossy, reason for this is because we humans have a body oil that keeps our skin moist, and this oil is not evenly distributed, and causes a soft reflection on our skin.
another factor for this could be sweat.
and the normal map is something you need to get the bumps and cracks in the skin. often in the lips, the eye region, and on men, often cracks in the forehead and on the chin. as for the image you linked, take a look at the lips, prime example there.
another good example is elder people, they have wrinkles and cracks all over their skin, a normal map would be essential in that case.
SSS + LIGHTING
thats all you need for now about texturing, but there is a whole other thing you must understand, and that is SSS (sub surface scattering) and how to light a character properly. Keylight, Backlight, Softbox, Rimlight, Fill light, you need to understand these terms and really know how to use them properly. A good light setup is the difference between an alright render, and a stunning one.
ohh, and how to make the maps, look it up.
Albedo maps are often just painted stright on to the model using Projection Painting. This can be done in Blender, but preferably in a pro texturing software such as substance painter, quixel, mari, etc.
can also be done in mudbox, and i believe zbrush too.
Roughness map can be done anywhere, just start with a black mask and paint more and more white where you believe the character is more glossy.
Normal map is baking. do research, baking is very simple but a bit hard to understand at first.
can be done in blender.