Это не моя вина.

• Это = this / it
• не = not
• моя = my
• вина = fault, blame, guilt

So literally, the sentence is something like This is not my fault or It is not my fault.

In Russian, the verb to be is usually omitted in the present tense.

So where English says:

• It is not my fault

Russian normally says:

• Это не моя вина

There is no present-tense есть here. Using есть would sound unnatural in this sentence.

Это often works like this or it in English.

In this sentence, it helps create the meaning It’s not my fault or That’s not my fault.

It is very common to use это in sentences that identify or label something:

• Это моя книга. = This is my book.
• Это не проблема. = It’s not a problem.
• Это не моя вина. = It’s not my fault.

You can sometimes omit it in context and just say Не моя вина, but Это не моя вина is a complete, neutral sentence.

Because моя has to agree with вина.

The noun вина is:

• feminine
• singular
• nominative

So the possessive my must also be feminine singular nominative:

• мой = masculine
• моя = feminine
• моё = neuter
• мои = plural

Since вина is feminine, you say:

• моя вина = my fault

Here вина is in the nominative singular form.

That is the dictionary form of the noun, and it is used here because the sentence is basically identifying something:

• Это не моя вина. = It is not my fault.

Russian often uses the nominative in this kind of present-tense identification sentence.

Also, even though there is не, that does not mean every following noun has to change case. The noun here is not a direct object; it is part of the statement of identity.

No. They only look a little similar in writing.

• вина = fault / guilt / blame
• вино = wine

They are completely different words.

This is a very common beginner confusion, so it is good to notice early.

Yes. Не моя вина is very natural in conversation.

It can mean:

• Not my fault.

This shorter version is common when the context is already clear.

Compare:

• Это не моя вина. = full sentence, neutral
• Не моя вина. = shorter, conversational, often more direct

Yes, but the basic order Это не моя вина is the most neutral.

Possible variants include:

• Это не моя вина. = neutral
• Не моя вина. = shorter, conversational
• Не моя это вина. = stronger emphasis on not mine

Russian word order is more flexible than English, but changes usually add emphasis or emotion rather than changing the core meaning.

For most learners, Это не моя вина is the safest default.

The stress is:

• Э́то не моя́ вина́.

A rough pronunciation guide:

• EH-ta ne ma-YA vee-NA

Notes:

• моя is stressed on the last syllable: моя́
• вина is also stressed on the last syllable: вина́
• это is stressed on the first syllable: э́то

They are similar, but not identical.

• Это не моя вина. = It’s not my fault.
• Я не виноват. = I am not to blame said by a man
• Я не виновата. = I am not to blame said by a woman

The first uses the noun вина (fault / blame). The second uses the short-form adjective виноват / виновата (guilty / to blame).

Both are common. The choice depends on what you want to focus on:

• the situation: Это не моя вина
• the person: Я не виноват / виновата

It is neutral and very common.

You can use Это не моя вина in:

• everyday conversation
• arguments
• explanations
• writing
• speech

It does not sound especially formal or especially slangy. It is a standard, natural sentence.

Not exactly. Моя is the possessive adjective my, not the standalone pronoun mine.

So:

• моя вина = my fault

Compare:

• Это моя книга. = This is my book.
• Эта книга моя. = This book is mine.

In your sentence, моя is directly describing вина, so it means my, not mine.