Your kitten has a cold/upper respiratory illness that is currently expressing itself with mucous discharge but will probably spread to sneezing etc. She needs eye cream applied to her eyes to prevent scaring/permanent eye damage and will need to go on a gentle antibiotic like Amoxicillin to prevent a bacterial infection from taking hold. A vet visit is indicated, you should *not* just wait it out, although if you got her from a shelter like the ASPCA you could contact them for support as well.
Cats with colds sometimes loose their appetite (due to inability to smell their food with congestion) so monitor her appetite and get assistance if it starts to wane, *before* she completely looses her desire to eat. If she were to stop eating completely she would be in trouble, and you or the vet would be hand-feeding (force feeding) her.