Learn Italian: I computer vecchi, li portano in discarica. - The old computers, they take them to the dump.

This is the main feature of left dislocation! When we move the direct object (I computer vecchi) to the very beginning of the sentence to make it the topic, Italian requires a matching clitic pronoun to resume or echo it before the verb. Since computer is treated as masculine plural here, we use the pronoun li.

Why is the plural of computer just computer?

Nouns borrowed from foreign languages generally do not change their endings in the plural in Italian. You can tell it is plural in this sentence because it is surrounded by plural words: the article I, the adjective vecchi, and the pronoun li.

Who is the subject of portano here?

The subject is an implied general they. Using a third-person plural verb like portano without a specific subject is a common way to express an impersonal action in Italian. It is the equivalent of saying people take them or they get taken in English.

Why do we use the preposition in for in discarica instead of alla?

Many words for everyday locations ending in -ca or -ia (such as banca, farmacia, and discarica) take the preposition in without a definite article. This is used when you are talking about going to that kind of place generally, rather than pointing out one specific building.