Il a oublié son rasoir; elle lui prête le sien.

He forgot his razor; she lends him hers.

Breakdown of Il a oublié son rasoir; elle lui prête le sien.

• il: he
• elle: she
• avoir: to have
• oublier: to forget

Questions & Answers about Il a oublié son rasoir; elle lui prête le sien.

What does the pronoun lui mean here, and why not le or la?

Lui is an indirect object pronoun meaning “to him” or “to her.” The verb prêter is used as prêter quelque chose à quelqu’un (“to lend something to someone”), so the person receives an indirect object pronoun: lui (singular) or leur (plural).
Le/La are direct object pronouns (“him/her/it”), which would replace the thing lent, not the person.

How does le sien work, and why not just son?

Le sien is a possessive pronoun meaning “hers/his (one),” and it replaces a noun already known from context. It agrees in gender and number with the thing possessed, not with the owner.

• Le sien = masculine singular (here, replacing rasoir).
  Son is a possessive adjective that must be followed by a noun (e.g., son rasoir). In our sentence we don’t repeat the noun, so we use the pronoun form le sien.

Could le sien mean “his” instead of “hers”? How do we know?

Yes, le sien can mean “his” or “hers.” It doesn’t show the owner’s gender; it only agrees with the thing possessed. Here, context tells us it’s “hers,” because the subject of the second clause is elle. If you need to remove ambiguity, add emphasis:

• Elle lui prête le sien à elle. (She lends him hers.)
• Or: Elle lui prête le sien, à elle, pas le sien à lui.