Learn Italian: Non trovi la tua rivista? Te la restituisco subito. - You cannot find your magazine? I am returning it to you immediately.

When you combine the indirect object pronoun ti (to you) with a direct object pronoun like la (it), the ti changes to te. This happens to make the combination easier to say. So, ti + la becomes te la.

What exactly does la refer to in te la?

la means "it" and refers to la rivista (the magazine). Because rivista is a feminine singular noun, we must use the feminine singular direct object pronoun la.

Why do te la come before the verb restituisco?

In Italian, object pronouns (whether single or combined) almost always go immediately before the conjugated verb. Here, they are placed right in front of restituisco (I return).

Why do we say la tua rivista instead of just tua rivista?

In Italian, you almost always need a definite article (like la, il, etc.) before a possessive word. Since rivista is feminine singular, you use la tua. The main exception is for singular family members, which drop the article.