Esta árvore é jovem.

Because árvore is a feminine noun in Portuguese, so the demonstrative has to agree with it.

• este = masculine singular
• esta = feminine singular

So:

• este livro = this book
• esta árvore = this tree

Even though a tree is not biologically female, Portuguese nouns still have grammatical gender.

Because grammatical gender in Portuguese is a property of the word, not necessarily of the real-world object.

So árvore is simply a feminine noun, and words that go with it must match:

• esta árvore
• a árvore
• árvore jovem or a árvore é jovem

There is not always a logical reason from English speakers’ point of view; it is just something you learn with the noun.

Because esta already works as a determiner, like this in English.

In Portuguese, you normally do not say:

• a esta árvore in this sentence structure

You simply say:

• esta árvore

Compare:

• a árvore = the tree
• esta árvore = this tree

So esta is already doing the job of specifying the noun.

Portuguese has two main verbs for to be: ser and estar.

Here, é is from ser, and it is used for a characteristic or classification: the tree is young.

• é jovem = is young

If you used está jovem, it would sound unusual in most normal contexts, because estar usually suggests a temporary state or condition. For age-related description like this, ser is the natural choice.

In Portuguese, descriptive adjectives often come after the noun.

So:

• árvore jovem
• casa grande
• menino feliz

In a full sentence with ser, you get:

• Esta árvore é jovem.

That word order is very normal. Portuguese can sometimes put adjectives before the noun, but that often changes the tone or style. Here, the basic and natural placement is after the noun in the underlying noun phrase, and in the sentence it appears after the verb.

Because jovem is one of many adjectives that have the same form for masculine and feminine singular.

So you can say:

• o menino é jovem
• a menina é jovem
• a árvore é jovem

No change is needed.

But the plural does change:

• os meninos são jovens
• as meninas são jovens
• estas árvores são jovens

So the singular is jovem, and the plural is jovens.

Traditionally:

• esta = this, near the speaker
• essa = that, near the listener
• aquela = that over there, farther away

So in a textbook-style distinction:

• esta árvore = this tree
• essa árvore = that tree
• aquela árvore = that tree over there

However, in everyday Brazilian Portuguese, many speakers use essa very often where textbooks might teach esta. So esta is absolutely correct, but in casual spoken Brazilian Portuguese you may hear essa more frequently.

They matter.

• árvore has an accent to show the stressed syllable: ÁR-vo-re
• é has an accent because it is the verb is

That also helps distinguish it from:

• e = and
• é = is

So:

• Pedro e Ana = Pedro and Ana
• Pedro é alto = Pedro is tall

In Portuguese, accents are not optional spelling decorations; they are part of the correct written form.

A rough English-friendly guide is:

ES-ta AR-vo-re eh ZHO-vehng

A few useful notes:

• Esta: stress on the first syllable
• árvore: stress on ÁR
• é: sounds like eh
• jovem: the j sounds like the s in measure, and the final -em is nasal in Brazilian Portuguese

This guide is only approximate, but it helps you get started.

Not with exactly the same meaning.

• jovem = young
• nova = new

So:

• Esta árvore é jovem. = The tree is young.
• Esta árvore é nova. = The tree is new.

For a tree, nova might suggest it was recently planted, while jovem focuses more on age or stage of growth. They are related ideas, but not the same.

You would change all the words that need plural agreement:

• Esta árvore é jovem.
• Estas árvores são jovens.

Changes:

• esta → estas
• árvore → árvores
• é → são
• jovem → jovens

This is a good example of how agreement works across the whole sentence in Portuguese.