Esta linha é longa.

Because linha is a feminine singular noun, and esta has to agree with it.

• este = masculine singular
• esta = feminine singular

So:

• este livro = this book
• esta linha = this line

In Portuguese, every noun has a grammatical gender, usually masculine or feminine. Linha happens to be feminine, so words connected to it also take feminine forms:

• esta linha
• a linha
• linha longa

This is grammatical gender, not biological gender.

No. Here, esta is a demonstrative adjective meaning this.

A very common beginner confusion is:

• esta = this (no accent)
• está = is from estar (with an accent)

Compare:

• Esta linha é longa. = This line is long.
• A linha está longa. = The line is long / has become long in a more situational sense

Because é is the verb is, from ser, and it is always written with an acute accent.

This matters because:

• é = is
• e = and

So the accent changes the word completely.

Portuguese often uses ser for a characteristic or description, and estar for a temporary state or condition.

Here, é longa is the normal, neutral way to say that the line is long as a description.

• é longa = it is long
• está longa = it is being long / has become long / is long at the moment

In many basic descriptive sentences, ser is the expected choice.

Because adjectives usually agree with the noun in gender and number.

Since linha is feminine singular, the adjective also has to be feminine singular:

• longo = masculine singular
• longa = feminine singular
• longos = masculine plural
• longas = feminine plural

So:

• um texto longo
• uma linha longa

Because this sentence uses a linking verb structure:

• Esta linha = subject
• é = linking verb
• longa = adjective describing the subject

So longa naturally comes after é.

This is similar to English:

• The line is long.

If you make it a noun phrase instead, Portuguese also usually puts the adjective after the noun:

• uma linha longa = a long line

A rough Brazilian Portuguese pronunciation is:

LEEN-ya

The important part is nh, which sounds like ny in words like canyon.

So the whole sentence is roughly:

ES-tah LEEN-ya eh LON-gah

Not exact, but close enough for a beginner.

Yes. In everyday Brazilian Portuguese, essa is very common, and in speech the distinction between esta and essa is often looser than in traditional grammar.

Traditional grammar says:

• esta = this, near the speaker
• essa = that / this near the listener or already mentioned

But in casual Brazilian usage, essa often appears where an English speaker might expect this.

So Esta linha é longa is correct, but Essa linha é longa is also very natural in many contexts.

No. Esta already determines the noun, so esta linha is complete by itself.

You normally say:

• Esta linha é longa.

Not:

• A esta linha é longa.

So in this sentence, no article is needed.

Yes, if the context makes it clear what esta refers to.

• Esta é longa. = This one is long.

Portuguese often leaves out the noun when it is already understood.

It would become:

Estas linhas são longas.

Notice that all the words that can change do change:

• esta → estas
• linha → linhas
• é → são
• longa → longas

This is a good example of Portuguese agreement working across the whole sentence.