Tu també has llegit aquesta notícia a internet?

Yes, it can be left out.

Catalan often omits subject pronouns because the verb ending already tells you who the subject is. Here, has already means you have, so tu is not grammatically necessary.

• Tu també has llegit aquesta notícia a internet?
• També has llegit aquesta notícia a internet?

Both are correct.

Including tu usually adds emphasis or contrast, something like You too?

També means also or too.

In this sentence, it comes after tu, so the idea is roughly Have you also read this article online? or You too have read this article online?

Its position helps show what is being emphasized. Here it naturally connects to the subject:

• Tu també... = you too / you also

Catalan adverbs like també can move around, but the emphasis changes slightly.

Has llegit is the present perfect: have read.

It is made with:

• has = you have
• llegit = past participle of llegir (read)

So:

• has llegit = you have read

Catalan uses this tense much like English does, especially for actions connected to the present or relevant now. In this question, the speaker is asking whether the person has already read the news item.

Has is the 2nd person singular present form of haver, the auxiliary verb used to form compound tenses.

So:

• jo he llegit = I have read
• tu has llegit = you have read
• ell/ella ha llegit = he/she has read

Even though haver also has an older meaning related to to have, in modern Catalan its main everyday role is as an auxiliary in tenses like this.

Because when Catalan forms a compound tense with haver, the past participle is normally invariable.

So even though notícia is feminine singular, the participle stays:

• has llegit aquesta notícia
• not has llegida aquesta notícia

This is different from some other Romance-language patterns learners may know. In standard modern Catalan, with haver, the participle generally does not agree with the object.

Yes, but it is important to notice that notícia is usually countable.

In English, news is normally uncountable:

• I read the news

In Catalan:

• una notícia = a news item / a piece of news / a news story
• aquesta notícia = this news item / this article / this story

So the sentence is talking about one specific item of news, not news in general.

Because notícia is a feminine singular noun.

The demonstrative must agree with the noun:

• aquest = masculine singular
• aquesta = feminine singular
• aquests = masculine plural
• aquestes = feminine plural

So:

• aquesta notícia = this news item / this article

Here a internet means on the internet / online.

This is a common way to express location in the digital space. You may also hear:

• per internet = via the internet / online
• sometimes other variants depending on region or style

A simple practical way to understand this sentence is:

• a internet = on the internet

Catalan usually does not need subject-auxiliary inversion the way English does.

English:

• Have you read this article?

Catalan can keep normal statement word order and rely on intonation in speech and the question mark in writing:

• Tu també has llegit aquesta notícia a internet?

So the structure is very natural in Catalan. You do not need to rearrange it to something equivalent to Have you... as English does.

Yes. Catalan word order is fairly flexible, especially with adverbs like també.

For example:

• També has llegit aquesta notícia a internet?
• Has llegit també aquesta notícia a internet?

These are possible, but the emphasis changes a bit.

• Tu també... emphasizes you too
• Has llegit també... emphasizes the idea of also reading
• Leaving out tu often sounds more natural unless you want contrast or emphasis

So the original sentence is completely correct, but it is not the only possible word order.