Это самый понятный ответ на мой вопрос.

In the present tense, Russian usually omits the verb быть (to be) in simple statements like this.

So:

• Это самый понятный ответ на мой вопрос. = This is the most understandable answer to my question.

There is no separate present-tense word for is here.

Compare:

• Это книга. = This is a book.
• Он врач. = He is a doctor.

If you put the sentence in the past or future, then forms of быть do appear:

• Это был самый понятный ответ. = This was the clearest answer.
• Это будет самый понятный ответ. = This will be the clearest answer.

Это here means this/this is and is very commonly used to identify or introduce something.

• Это ответ. = This is an answer.
• Это мой брат. = This is my brother.

By contrast, этот is a demonstrative adjective meaning this, and it must go directly with a noun:

• этот ответ = this answer
• этот вопрос = this question

So:

• Это самый понятный ответ... = This is the clearest answer...
• Этот самый понятный ответ... would mean This clearest answer..., which is a different structure and usually not what you want here.

Самый is used to form the regular superlative in Russian: the most ...

So:

• понятный = understandable / clear
• самый понятный = the most understandable / the clearest

That makes:

• самый понятный ответ = the clearest answer / the most understandable answer

This is one of the most common ways to make a superlative in Russian.

More examples:

• самый важный вопрос = the most important question
• самая интересная книга = the most interesting book
• самое трудное задание = the most difficult task

Понятный is an adjective, and its ending shows that it agrees with ответ.

• ответ is masculine
• singular
• nominative

So the adjective must match:

• понятный ответ

If the noun changed, the adjective would change too:

• понятная книга = understandable book
• понятное объяснение = understandable explanation
• понятные ответы = understandable answers

Because самый behaves like an agreeing word too, it also changes with the noun:

• самый понятный ответ
• самая понятная книга
• самое понятное объяснение
• самые понятные ответы

It is in the nominative because it is the main noun being identified after Это.

The sentence is basically:

• This = the clearest answer to my question

In this kind of identifying statement, Russian commonly uses the nominative for the noun phrase:

• Это хороший ответ.
• Это мой друг.
• Это важный вопрос.

So:

• самый понятный ответ stays in the nominative singular masculine

Because Russian uses the fixed expression:

• ответ на вопрос = answer to a question

This is just the normal preposition and case pattern used with ответ.

So:

• ответ на мой вопрос = answer to my question
• literally: answer onto my question, but you should think of it simply as answer to

This is something best learned as a chunk:

• ответ на письмо = answer to a letter
• ответ на сообщение = answer to a message
• ответ на вопрос = answer to a question

Because after на in this expression, вопрос is in the accusative case:

• ответ на что? = answer to what?
• на мой вопрос = to my question

Now, вопрос is a masculine inanimate noun, and in the singular, its accusative form is the same as the nominative:

• nominative: мой вопрос
• accusative: мой вопрос

That is why it looks unchanged.

Compare with a feminine noun, where you can see the accusative more clearly:

• ответ на мою просьбу = answer to my request

Here моя просьба becomes мою просьбу.

No. It is the most straightforward and common way, but not the only one.

Russian has more than one way to express a superlative idea:

1. самый + adjective

   • самый понятный
   • the most understandable / the clearest

2. Sometimes наиболее + adjective

   • наиболее понятный
   • more formal, often found in writing or official style

In everyday speech, самый понятный is the most natural choice here.

It mainly means understandable, easy to understand, or clear in the sense of being easy to follow.

So самый понятный ответ can be translated in several natural ways:

• the most understandable answer
• the clearest answer
• the easiest answer to understand

The exact English translation depends on context. In this sentence, clearest answer is often the most natural English choice.

Yes. Russian word order is flexible, and changing it can shift the emphasis.

The neutral version is:

• Это самый понятный ответ на мой вопрос.

You could also hear:

• На мой вопрос это самый понятный ответ.
  • emphasizes to my question
• Самый понятный ответ на мой вопрос — это этот.
  • a more contrastive structure, something like The clearest answer to my question is this one.

But for a simple, neutral statement, the original order is the best one to learn first.

The main stresses are:

• Э́то
• са́мый
• поня́тный
• отве́т
• на
• мой
• вопро́с

So the sentence sounds roughly like:

• Э́то са́мый поня́тный отве́т на мой вопро́с.

Stress matters in Russian, so it is worth learning words together with their stressed syllables.

Sometimes, yes, but the meaning changes slightly.

• Это самый понятный ответ на мой вопрос. = This is the clearest answer to my question.

If you say:

• Самый понятный ответ на мой вопрос.

that is no longer a full neutral statement by itself in the same way. It sounds more like:

• a sentence fragment,
• a heading,
• or something said in a context where the omitted part is obvious.

So if you want the full meaning This is the clearest answer to my question, keep Это.

You would say:

• Это не самый понятный ответ на мой вопрос.

Here не goes before the phrase you are negating.

That means:

• This is not the clearest answer to my question.

If you wanted This is the most unclear answer, that would be different:

• Это самый непонятный ответ на мой вопрос.

So:

• не самый понятный = not the clearest
• самый непонятный = the most unclear / the least understandable

Yes, you could.

• самый понятный = the most understandable
• наиболее понятный = the most understandable

The difference is mostly stylistic:

• самый понятный sounds more everyday and conversational
• наиболее понятный sounds more formal or written

For normal speech, самый понятный is usually the better choice.