In the feline world, licking is not only a way to clean one's fur, but also a social behavior. When a cat licks another cat, it usually means they are building a relationship, increasing mutual trust and friendship. Therefore, when a cat licks your face, it can be understood as it trying to establish a closer relationship with you, expressing its affection and trust.
Furthermore, a cat licking your face can also be a way of asserting dominance. In the cat world, higher-ranking cats will lick lower-ranking cats to demonstrate their authority. While domestic cats don't usually experience genuine fear or respect for humans, they still retain some of this instinctive behavior.
