Warm milk will clear up that eye,,,we had a kitten with that problem, both eyes closed with scabs, my cousin Terry said use warm milk to clean the scab,,,,it was a amazing, we named the kitten Bright Eyes.
It's an eye infection. In a kitten that age, it's likely caused by calcivirus... has the mother been tested???
Unless the kitten gets antibiotics within a day of when the infection started to get severe, there's a good chance it will end up with full or partial blindness (assuming it lives).
Your options are take it to a vet, or try to find some amoxicillin to give to kitty. If this is a human pill, we're talking about a pin drop amount of medication here.