Learn Hardcore Italian: Quando lo vedo glielo restituisco: quel rasoio è costoso. - When I see him I’ll give it back to him: that razor is expensive.

Lo is the third-person masculine singular direct object pronoun. Here it means “him” (the person who borrowed the razor). So Quando lo vedo literally is “When I see him.”

How do the pronouns in glielo restituisco work?

Glielo is a single clitic cluster combining two pronouns:

gli = “to him” (indirect object)
lo = “it” (direct object, the razor)
Putting them together, glielo restituisco means “I return it to him.”

Why must I say glielo instead of gli lo restituisco?

Italian does not allow two separate clitics in a row. Instead, when you need both an indirect and direct object pronoun, you merge them into one form according to these rules:

mi + lo → melo
ti + la → tela
gli + lo → glielo
… and so on. You never split them as gli lo; you must use glielo.

Why are the pronouns placed before the verbs (e.g. lo vedo, glielo restituisco)?

In Italian, clitic object pronouns normally appear before finite verbs (this is called proclisis). So you say:

lo vedo (not vedo lo)
glielo restituisco (not restituisco glielo)

The one exception is the affirmative imperative (e.g. dammelo, “give it to me”), but here both verbs are indicative, so the pronouns come first.

Why is the present tense used here if the action happens in the future (“I will return it”)?

After conjunctions of time like quando, Italian often uses the present indicative to express future actions, especially in spoken language.

Quando lo vedo, glielo restituisco.
literally “When I see him, I return it to him,” but in context it means “When I see him, I will return it to him.”

You can also use the future tense (Quando lo vedrò, glielo restituirò), but it sounds more formal or bookish.

Why is quel used before rasoio, instead of quello or quell’?

Italian’s demonstrative quello changes form depending on the following sound:

quel before most consonants: quel rasoio
quello before s+consonant or z: quello studente, quello zaino
quell’ before a vowel: quell’uomo
quella / quelle in the feminine, etc.
Since rasoio begins with r, you use quel rasoio.

Why is there a colon before quel rasoio è costoso?

The colon introduces an explanation or justification of the previous statement. In this sentence, it tells us why you want to return the razor promptly:
…glielo restituisco: quel rasoio è costoso.
“…I’ll give it back to him: that razor is expensive.”

Can I change the word order to put the time clause at the end?

Yes. Italian allows you to move the subordinate clause:

Glielo restituisco quando lo vedo.
This reverses the order but keeps the same meaning: “I’ll give it back to him when I see him.”

Why is the adjective costoso placed after the verb è instead of before rasoio?

Here costoso is used predicatively with the copula essere, so it comes after the verb:
quel rasoio è costoso (“that razor is expensive”).
If you wanted to use costoso as an attributive adjective (directly modifying the noun), you could say un costoso rasoio, but that slightly changes the nuance and is less common in everyday speech.