It can be territorial because she wants to leave her scent on you. From a young age, a cat’s mother licks them to clean and comfort them, but it also re-establishes her scent. So when your cat licks you and gives you kisses, she is claiming you as her own.
As for affection, she feels comfort in you petting her and sees that as you grooming her, so she gives you kisses to clean and groom you back. This also stems back from when she was a kitten and her mother licked her clean from debris.
But what if there is excessive licking? If your cat has never given you kisses before but all of a sudden starts and then starts licking themselves vigorously, it could be a sign that something is wrong. Excessive licking can be a sign that she has a skin irritation, fleas, or ticks. It is best to take her to the vet and get recommended treatments for her ailments.
So now we know that when your cat is giving you kisses, it is a true sign of affection and she is claiming you as her own. She is letting you know that she loves you and she also appreciates the love and cuddles you are giving her.