Hi Mam!

I am confused about how to do this problem.

NaF is completely soluble in water, so it dissociates to give Na⁺(aq) and F⁻(aq). The fluoride ion, F⁻, is the conjugate base of the weak acid HF, so it behaves as a Brønsted–Lowry base (proton acceptor) in water. Water, in this reaction, acts as the Brønsted–Lowry acid (proton donor).

Hydrolysis equation (definition-based):

F-(aq) + H2O(l) <--> HF(aq) + OH-(aq)

F⁻ accepts H⁺ → forms HF

H₂O donates H⁺ → forms OH⁻

Because HF is weak, the equilibrium lies mostly to the left, but enough OH⁻ forms to make the solution basic.