Esta palabra significa combustible.

Because palabra is a feminine noun in Spanish, so the demonstrative has to match it.

• esta = this, for feminine singular nouns
• este = this, for masculine singular nouns

So:

• esta palabra = this word
• este libro = this book

Even though palabra ends in -a, which often signals feminine, the main reason is simply that palabra is grammatically feminine.

In Spanish, grammatical gender is usually not about biological sex. Many inanimate things are either masculine or feminine just as part of the language.

So la palabra is feminine because that is its grammatical gender, not because a word is “female.”

You just learn it as:

• la palabra
• esta palabra
• una palabra

A useful detail: some nouns that end in -ma are masculine, like el problema, but palabra is a regular feminine noun.

Because esta already works like this in English and directly modifies the noun.

• esta palabra = this word

You do not add la here. In Spanish, you normally say either:

• la palabra = the word
• esta palabra = this word

Not esta la palabra.

Because the sentence is talking about meaning, not identity.

• Esta palabra significa combustible. = This word means fuel.
• Esta palabra es combustible. would mean something like This word is fuel, which does not make sense in the same way.

So significar is the correct verb when you want to explain what a word means.

Significa is the third-person singular present tense form of significar.

It can mean:

• it means
• he/she means, depending on context

Here, the subject is esta palabra, which is singular, so:

• esta palabra significa = this word means

Other forms:

• yo significo = I mean
• tú significas = you mean
• él/ella significa = he/she means
• esta palabra significa = this word means

Because significar can take a direct object directly.

• Esta palabra significa combustible.
• literally: This word means fuel.

You only use que in certain structures, such as when what follows is a whole clause:

• Eso significa que no viene. = That means that he/she isn’t coming.

But with a single noun like combustible, no que is needed.

Because combustible here is being used as the meaning or label itself, not as a specific, identified noun phrase.

• Esta palabra significa combustible. = This word means fuel.

This is similar to English, where you usually say means fuel, not means the fuel.

If you added an article, the meaning would change or sound unnatural in this context.

Not necessarily. Combustible usually means fuel in a broad sense.

Depending on context, it can refer to:

• fuel in general
• something combustible
• in some contexts, fuel for vehicles

In some countries, people may use it in contexts where English speakers might specifically think of gas or gasoline, but the core meaning is broader: fuel.

So in this sentence, it is best understood as the meaning of the word combustible, not necessarily just one exact type of fuel.

Yes. Combustible can be both a noun and an adjective.

As a noun:

• El combustible es caro. = Fuel is expensive.

As an adjective:

• material combustible = combustible material / flammable material

In your sentence, combustible is functioning as the meaning of the word, so it is basically being treated as a vocabulary item rather than described only by its part of speech.

Yes. That is very natural and common.

• Esta palabra significa combustible.
• Esta palabra quiere decir combustible.

Both can mean This word means fuel.

A small nuance:

• significar can sound a little more direct or dictionary-like
• querer decir is extremely common in everyday speech

Both are correct.

Both are demonstratives, but they point to different distances.

• esta palabra = this word
• esa palabra = that word

In practice:

• esta usually refers to something closer to the speaker, or something currently being discussed very directly
• esa often refers to something a bit farther away, or previously mentioned

So if you are pointing to a word right in front of you or on the page you are discussing, esta palabra makes perfect sense.

A simple pronunciation guide is:

EH-sta pah-LAH-bra sig-nee-FEE-ka com-boos-TEE-ble

A few helpful notes:

• esta: the e sounds like the e in met
• palabra: stress is on LA
• significa: the g before n stays hard; stress is on FI
• combustible: stress is on TI

More natural rhythm: Esta palabra significa combustible.

Also, in most of Latin America:

• c before o sounds like k
• b and v are pronounced very similarly
• the r in palabra is a light tap

Because Spanish often omits subject pronouns when the verb form already shows who or what the subject is.

In English, you would say:

• This word means fuel.

In Spanish, the subject is already stated as esta palabra, so there is no need for any extra pronoun.

Even when the subject is not repeated, Spanish often leaves it out:

• Significa combustible. = It means fuel. / This means fuel.

Spanish is a pro-drop language, which means subject pronouns are often unnecessary.

A little, but the original order is the most natural and neutral.

Standard order:

• Esta palabra significa combustible.

You could change the structure in special contexts, but it may sound marked or unnatural for a basic statement.

For example:

• Combustible significa esta palabra is not the normal way to say it

So for learners, the best pattern to remember is:

• [demonstrative] + [noun] + [verb] + [meaning]
• Esta palabra significa combustible.