La estatua es de piedra.

Because estatua is a feminine noun in Spanish, so it takes the feminine article la.

• la estatua = the statue
• una estatua = a statue

Even though some nouns can be tricky, estatua is straightforwardly feminine.

Spanish has two verbs for to be: ser and estar.

Here, es comes from ser, which is used for:

• identity
• general characteristics
• what something is made of

Since de piedra describes the statue’s material, ser is the correct choice:

• La estatua es de piedra.

Using está here would sound wrong in standard Spanish.

Here, de means made of.

So de piedra means made of stone.

This use of de is very common in Spanish:

• La mesa es de madera. = The table is made of wood.
• El anillo es de oro. = The ring is made of gold.

Depending on context, de can also mean of, from, or about, but in this sentence it refers to material.

In Spanish, when you say what something is made of, you often use de + material noun without an article.

So:

• de piedra
• de madera
• de metal
• de vidrio

That is why de la piedra would not sound natural here. De la piedra would usually mean something more specific, like from the stone or of the stone, not simply made of stone.

Usually piedra means stone, especially in contexts like materials, buildings, or statues.

Examples:

• una casa de piedra = a stone house
• una estatua de piedra = a stone statue

In some contexts, English rock and stone overlap, but here stone is the best translation.

Because Spanish often leaves out subject pronouns when they are not needed.

The verb es already tells you the subject is he/she/it or you formal, and here the noun la estatua is explicitly stated, so there is no need to add a pronoun.

Spanish prefers:

• La estatua es de piedra.

Not:

• La estatua ella es de piedra.

That second version sounds unnatural.

Yes. This sentence follows a very similar order:

• La estatua = the statue
• es = is
• de piedra = made of stone

So it works like:

subject + verb + complement

That makes this sentence quite easy for English speakers to understand.

A common Latin American pronunciation is approximately:

ehs-TA-tu-ah

A few helpful points:

• The e at the beginning is fully pronounced.
• The stress is on ta: es-TA-tua
• The u is pronounced, unlike in some combinations such as gue or gui

So do not pronounce it like English statue. Say each vowel clearly.

Yes. That is also correct.

• La estatua es de piedra. = The statue is made of stone.
• La estatua está hecha de piedra. = The statue is made of stone.

The second version is a little more explicit because hecha de literally means made of. Both are natural, but es de piedra is shorter and very common.

Yes, piedra is feminine, and its ending -a matches the common pattern for feminine nouns:

• la piedra
• una piedra

But remember, noun gender in Spanish is not always predictable just from the ending. In this case, though, piedra is feminine and follows the usual pattern.

No, not in normal Spanish.

To express material, Spanish needs de:

• La estatua es de piedra.

Without de, the sentence sounds incomplete or incorrect because piedra is not being linked properly as the material.

It would be:

Una estatua es de piedra.

That means A statue is made of stone, though in many contexts it may sound more general or less natural unless you are talking about a particular kind of statue.

If you mean one specific statue but it has not been introduced yet, una estatua de piedra is also very common as a noun phrase:

• Vi una estatua de piedra. = I saw a stone statue.