Это полная неправда.

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

So where English says:

• This is a complete lie
• That is completely untrue

Russian often just says:

• Это полная неправда.

Literally, it looks like This/That complete untruth, but the meaning is naturally This/That is a complete lie / totally untrue.

If you put the sentence into the past or future, a form of быть appears:

• Это была полная неправда. = That was completely untrue.
• Это будет неправда. = That will be untrue.

Это is very flexible. In sentences like this, it often works like this, that, or even it, depending on context.

So:

• Это полная неправда. can mean
  
  • This is a complete lie.
  • That is completely untrue.
  • It’s totally untrue.

Russian does not always distinguish as sharply as English between this and that in this kind of structure.

Also, это is often used in identification statements:

• Это мой брат. = This/That is my brother.
• Это проблема. = This/That is a problem.

Because полная has to agree with неправда, and неправда is a feminine singular noun.

Russian adjectives agree with the noun in:

• gender
• number
• case

Here:

• неправда = feminine, singular, nominative
• so the adjective must also be feminine, singular, nominative:
  • полная

Compare:

• полный текст = a full text (masculine)
• полное имя = a full name (neuter)
• полная неправда = complete untruth / a complete lie (feminine)

Because nouns in Russian have grammatical gender, and неправда is a feminine noun.

A very common pattern is:

• nouns ending in -а / -я are often feminine

So:

• правда = truth (feminine)
• неправда = untruth / falsehood / lie (also feminine)

This gender is a grammatical property of the noun, not something related to real-world sex.

They are close, but not always identical in tone.

Неправда literally means not-truth, so it often means:

• untruth
• falsehood
• that’s not true
• sometimes lie

Ложь is also lie / falsehood, but it can sound a bit more direct, weighty, or formal.

In many everyday situations, неправда feels very natural, especially when reacting to something someone said:

• Это неправда! = That’s not true!

Adding полная makes it stronger:

• Это полная неправда. = That is completely untrue.

So in this sentence, неправда is a very common and idiomatic choice.

Yes, literally полная means full / complete, so the phrase literally looks like complete untruth.

But in natural English, the best translations are usually things like:

• complete nonsense
• completely untrue
• a complete lie
• utterly false

So this is one of those places where a literal word-for-word translation is helpful for understanding structure, but not always best for natural English style.

It is in the nominative case.

This sentence is an example of an identifying or equational sentence:

• Это полная неправда.

The noun phrase after это is in the nominative:

• полная неправда

That is why you do not see forms like неправду here.

Compare:

• Это неправда. = nominative
• Я слышу неправду. = accusative, because it is a direct object

So in your sentence, полная неправда is naming what это is.

Yes, absolutely.

• Это неправда. = That’s not true.
• Это полная неправда. = That’s completely untrue / a complete lie.

Adding полная makes the statement stronger and more emphatic.

You can think of it roughly like the difference between:

• That’s not true.
• That’s completely untrue.

Yes, Russian word order is flexible, but the neutral and most natural order here is:

• Это полная неправда.

You may also see:

• Полная неправда.
  This can work as a short, forceful reaction: Complete nonsense.

• Неправда это.
  This is possible, but it sounds marked or emphatic, often emotional or contrastive.

For a learner, the safest default is:

• Это полная неправда.

The stress is:

• Э́то по́лная непра́вда.

A rough pronunciation guide:

• Э́то = EH-tuh
• по́лная = POL-nuh-ya
• непра́вда = nee-PRAV-duh

A more careful note:

• the о in unstressed positions is reduced in normal speech
• the ending -ая in полная is pronounced more like -aya / -əjə, depending on speed and accent

But for learning purposes, stressing the right syllables is the most important part:

• Э́то по́лная непра́вда.

Because неправда is an established noun meaning untruth / falsehood / lie.

Russian не is sometimes written together with a word and sometimes separately. In this case, неправда is a standard dictionary word.

So:

• правда = truth
• неправда = untruth / falsehood

This is similar to English having both:

• truth
• untruth

In many contexts, Это неправда is the standard phrase for That’s not true.

It is mostly neutral to strong, depending on intonation.

• Это неправда. is a normal, common way to say That’s not true.
• Это полная неправда. is stronger and more emphatic.

It can sound:

• calm and firm
• argumentative
• indignant, if said with strong emotion

So the grammar itself is neutral, but the adjective полная adds force.

Yes. Russian often uses adjectives or adverbs to intensify this kind of statement.

For example:

• Это неправда. = That’s not true.
• Это полная неправда. = That’s completely untrue.
• Это абсолютная неправда. = That’s absolutely untrue.
• Это чистая неправда. = That’s sheer falsehood.
• Это сущая неправда. = That’s utter nonsense / complete falsehood.

Each has a slightly different tone, but полная неправда is very common and easy to use.

Yes, you can.

• Это ложь. = That’s a lie.
• Это полная неправда. = That’s completely untrue.

The difference is mostly in nuance:

• Это ложь can sound more direct and accusatory
• Это полная неправда can sound a bit broader: not true at all, completely false

Depending on context, both can work. If you want a very common and idiomatic phrase for rejecting a statement, Это неправда and Это полная неправда are excellent choices.