Её вокальный диапазон широкий, но она поёт фальшиво.

Here её means her in the possessive sense: her vocal range.

A useful thing to know is that её can function in two different ways:

• as a form of the pronoun она (her)
• as the possessive her

In this sentence, it is possessive:

• Её вокальный диапазон = Her vocal range

Unlike many other Russian words, possessive его / её / их do not change to agree with the noun that follows. So you get:

• её голос = her voice
• её песня = her song
• её способности = her abilities

The form stays её.

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

So:

• Её вокальный диапазон широкий literally looks like Her vocal range wide
• but it means Her vocal range is wide

This is completely normal in Russian.

Compare:

• Он студент. = He is a student.
• Она счастлива. = She is happy.
• Диапазон широкий. = The range is wide.

If you want past or future, then forms of быть appear:

• Её вокальный диапазон был широким. = Her vocal range was wide.
• Её вокальный диапазон будет широким. = Her vocal range will be wide.

Because широкий agrees with диапазон, and диапазон is:

• masculine
• singular
• here, in the nominative

So the adjective must also be masculine singular nominative:

• широкий диапазон

You can see the same agreement pattern in other genders:

• широкая улица = a wide street
• широкое море = a wide sea
• широкие возможности = wide opportunities

Even though широкий comes after the noun here, it still agrees with диапазон.

Because here широкий is part of the predicate, not just a regular descriptive adjective inside the noun phrase.

There is an important difference:

• широкий вокальный диапазон = a wide vocal range
  
  • adjective directly modifies the noun
• вокальный диапазон широкий = the vocal range is wide
  
  • adjective is predicative

So in your sentence:

• Её вокальный диапазон широкий = Her vocal range is wide

This is tied to the omitted present-tense is.

Вокальный means vocal, especially in connection with singing.

So:

• вокальный диапазон = vocal range

It refers to the range of notes a person can sing.

It is not exactly the same as voice. For example:

• голос = voice
• вокальный диапазон = vocal range

A native speaker would normally say вокальный диапазон for the musical idea of vocal range.

Because но means but, and it joins two separate clauses.

The two clauses are:

• Её вокальный диапазон широкий
• она поёт фальшиво

In Russian, when two full clauses are joined by но, a comma is normally required:

• ..., но ...

This is very standard punctuation.

Yes, Russian can sometimes omit pronouns, but here она sounds natural and clear because the sentence has a strong contrast:

• Her vocal range is wide, but she sings off-key.

Repeating она helps balance the two parts:

• Её вокальный диапазон широкий, но она поёт фальшиво.

You could hear:

• Её вокальный диапазон широкий, но поёт она фальшиво.

That version is also possible, but the emphasis changes. It puts more stress on она or on the contrast in how she sings.

For a learner, the given version is the most straightforward and neutral.

Поёт is the 3rd person singular present-tense form of петь (to sing).

So:

• я пою = I sing / am singing
• ты поёшь = you sing
• она поёт = she sings / is singing

A very important point: the letter ё is pronounced yo, and it is always stressed.

So поёт is pronounced approximately:

• pa-YOT

not like поет with plain е.

Also, in real Russian texts, ё is sometimes written as е, so you may see поет, but it is still understood as поёт.

It can mean either, depending on context.

Russian present tense often covers both:

• She sings
• She is singing

In this sentence, because it describes her general ability or manner, the natural meaning is:

• she sings
• or more specifically, she sings off-key

So it sounds like a general statement about her singing, not necessarily about one single performance happening right now.

Here фальшиво means off-key, out of tune, or falsely in pitch.

In musical contexts, it is commonly used to say that someone is not singing the notes correctly.

So:

• она поёт фальшиво = she sings off-key

The word comes from фальшивый, which can mean things like:

• false
• fake
• insincere
• off-key

But in this sentence, the musical meaning is the one that matters.

Yes, but the meaning would be less specific.

• Она поёт плохо. = She sings badly.
• Она поёт фальшиво. = She sings off-key / out of tune.

So:

• плохо is broader
• фальшиво specifically points to incorrect pitch

If you want to say that her singing is technically bad in a general sense, плохо works. If you want to say she misses the notes, фальшиво is better.

Sometimes learners want to say big range, but for range, Russian naturally uses широкий much more often.

So:

• широкий диапазон = natural, standard
• большой диапазон = understandable, but less idiomatic here

Russian often uses широкий with abstract ideas like range, scope, choice, possibilities:

• широкий выбор = a wide choice
• широкие возможности = broad opportunities
• широкий диапазон = wide range

So широкий is the best choice in this sentence.

Yes. Russian word order is flexible, but changing it often changes emphasis.

The original sentence is neutral and natural:

• Её вокальный диапазон широкий, но она поёт фальшиво.

Other possible orders include:

• Она поёт фальшиво, но её вокальный диапазон широкий.
  This starts with the more surprising or negative point.

• Но поёт она фальшиво.
  This emphasizes она or the contrast more strongly.

• Фальшиво она поёт.
  This is even more marked and expressive.

For learners, the original version is a good default because it is clear and stylistically neutral.