Se is the reflexive pronoun for the third person singular matching él (he) or ella (she). In Spanish, we use Reflexive Pronouns with a verb to point out that a person carries out an action to or for himself or herself. So here Olivia carries out the action for herself, that is, she washes her face. Finally:
Olivia se lava la cara
Translates into:
Olivia washes her face.
Answer:
Olivia se lava la cara
Explanation:
Olivia se lava la cara
