В этом предложении есть вопросительное слово.

Because after в you can get different cases depending on the meaning.

• в + Prepositional = in / inside / within
• в + Accusative = into / to / entering

Here the sentence means in this sentence, so Russian uses the Prepositional case:

• в этом предложении = in this sentence

If you said в это предложение, that would suggest motion into the sentence, which does not fit here.

Because этот has to agree with предложении in gender, number, and case.

The dictionary form is:

• этот = this for a masculine noun

But предложение is:

• neuter
• singular
• here in the Prepositional case

So этот changes to the matching form:

• в этом предложении

A few related forms:

• это предложение = this sentence
• в этом предложении = in this sentence

Because предложение is in the Prepositional case after в when it means in.

Base form:

• предложение = sentence

Prepositional singular:

• в предложении = in the sentence

This noun ends in -ие, and nouns of this type often have -ии in the Prepositional singular:

• здание → в здании
• предложение → в предложении

So предложении is just the correct case form of предложение here.

Here есть means something like there is / there exists.

So:

• В этом предложении есть вопросительное слово. = There is an interrogative word in this sentence.

Yes, Russians do use есть in this kind of sentence, especially when they want to say that something is present somewhere.

Compare:

• У меня есть книга. = I have a book. / There is a book with me.
• В комнате есть стол. = There is a table in the room.

However, Russian often omits the verb to be in the present tense when simply linking subject and predicate:

• Это книга. = This is a book.

But in existential sentences like there is/there are, есть is very common.

Because in a sentence with есть meaning there is, the thing that exists is usually in the Nominative case.

So here:

• в этом предложении = location
• есть = there is
• вопросительное слово = the thing that exists there

That is why слово stays in the nominative singular.

It means interrogative word or, in more learner-friendly English, a question word.

• вопрос = question
• вопросительный = interrogative / question-related
• слово = word

So вопросительное слово is a word like:

• кто = who
• что = what
• где = where
• когда = when
• почему = why

In everyday English explanations for learners, question word is often the easiest translation.

Because the adjective must agree with the noun.

• слово is neuter singular
• so the adjective must also be neuter singular

That gives:

• вопросительное слово

Compare the adjective in different genders:

• вопросительный = masculine
• вопросительная = feminine
• вопросительное = neuter

Since слово is neuter, вопросительное is the correct form.

The given word order is natural and neutral:

• В этом предложении есть вопросительное слово.

It starts with the location/topic in this sentence, then says that something exists there.

You could change the order, but the emphasis would shift. For example:

• Вопросительное слово есть в этом предложении.

This is grammatically possible, but it sounds more marked or contrastive, as if emphasizing the interrogative word.

For a basic, neutral statement, the original order is the best choice.

A rough pronunciation guide for an English speaker is:

• v EH-tam prad-la-ZHE-ni-ee yest va-pra-SEE-tyel-na-ye SLO-va

A few helpful notes:

• в is like v
• э in этом is like e in met
• ж in предложении sounds like s in measure
• есть is pronounced roughly like yest
• unstressed о often sounds more like a in actual speech

This is only approximate, but it should help you recognize the sentence when spoken.

Russian has no articles like a/an or the.

So слово by itself can mean:

• a word
• the word

The exact meaning depends on context.

In this sentence, English naturally uses a:

• There is a question word in this sentence.

But Russian does not need a separate word for that. Context carries the meaning.