How can I fix these marks on my face?

Vitamin E.

Get a glycolic tonor. I like the DDF Glycolic 10%. It will sting at first (so I wouldn’t use it right after you shave) but it will fade any discoloration after a few weeks.

I get that from smoking a lot. It discolored my hair. Kind of a bummer.

Are you talking about ingrown hairs from shaving or dark pigmentation. I do not know if you are male or female. If you are male than chances are you are talking about the shadow that happens to most men who shave. Not much you can do about that. At least I haven’t seen a discovery for men about that.
See a dermatologist if it is ingrown hair. They can give you something for that.
If it is just too much melanin than a dermatoligist can suggest ways to lighten it but once you stop most treatments it will just come back.
Now if it cause by some injury to the skin like pimples or cuts while saving, than vitamin E and taking vitamin A can help. Have your blood check and see if maybe you are lacking any vitamins. Your skin needs vitamin C, E and A and D to function well.
If these don’t seem to follow any of the reasons listed above and is a sudden change than see a doctor. Our skin, hair, eyes and nails often mirror bad health issues we are not aware of.
if it is ingrown hairs caused by shaving. Then don’t reuse old worn blades and be sure to use after shave lotion to sterilize the area shaven and reduce any new bumps. If you can see any of the hairs and pull them out with tweezers and sterilize afterwards, that will give the bump time to heal before the new growth. With time it will go away and you will get less and less. I use to tweeze my husbands and he got less with time. After he switched to a 3 blade shaver he hasn’t had problems with them.