Её голос ровный и спокойный.

Here её means her in the possessive sense: her voice.

In this sentence, её is being used like a possessive word before a noun, just like my, your, her in English.

A useful thing to know: Russian его, её, and их often work as possessive words meaning:

• его = his
• её = her
• их = their

So:

• её голос = her voice
• его голос = his voice
• их голос = their voice

Unlike many other Russian pronouns, these possessive forms do not change to match the gender or number of the noun after them.

In Russian, the verb to be is usually not expressed in the present tense.

So where English says:

• Her voice is calm

Russian simply says:

• Её голос спокойный

That means ровный и спокойный works as the predicate without any present-tense is.

If you were talking about the past or future, Russian would use forms of быть:

• Её голос был спокойным. = Her voice was calm.
• Её голос будет спокойным. = Her voice will be calm.

Because they describe голос, and голос is a masculine singular noun.

Russian adjectives must agree with the noun they describe in:

• gender
• number
• case

So:

• голос = masculine singular
• therefore ровный and спокойный must also be masculine singular

Compare:

• ровный голос = an even/steady voice
• ровная речь = even/steady speech
• ровное дыхание = even breathing
• ровные звуки = even sounds

Same idea with спокойный:

• спокойный голос = calm voice
• спокойная музыка = calm music
• спокойное море = calm sea

Голос is in the nominative case because it is the subject of the sentence.

The structure is basically:

• Её голос = the subject
• ровный и спокойный = what is being said about the subject

So this is a very common Russian sentence pattern:

• [subject in nominative] + [adjective/adjectives]

For example:

• Дом большой. = The house is big.
• Море спокойное. = The sea is calm.
• Её голос ровный и спокойный.

Yes, ровный literally has meanings like even, level, smooth, steady, depending on context.

With голос, it usually means something like:

• steady
• even
• level
• without shakiness or sudden emotional changes

So ровный голос suggests a voice that is controlled, consistent, and not trembling or erratic.

It is not exactly the same as calm, which is why the sentence uses both:

• ровный = steady/even
• спокойный = calm

Together they reinforce the impression of a controlled, peaceful voice.

They are similar, but not identical.

• ровный focuses more on the quality or steadiness of the voice
• спокойный focuses more on the emotional tone of the voice

So:

• ровный голос = a voice that does not shake, jump, or break
• спокойный голос = a voice that sounds calm and not upset

Using both is natural and gives a fuller description.

Because ровный and спокойный are simply two adjectives joined by и = and.

Russian does not put a comma before и when two words are connected in a simple pair like this:

• ровный и спокойный
• умный и добрый
• большой и светлый

So the sentence is correctly written:

• Её голос ровный и спокойный.

Yes, word order in Russian is flexible, but the meaning or emphasis can shift.

The most neutral version here is:

• Её голос ровный и спокойный.

Other possibilities:

• Голос у неё ровный и спокойный.
  This is natural too, and can sound a bit more like As for her voice, it is steady and calm or She has a steady, calm voice.

• Голос её ровный и спокойный.
  This is possible, but less neutral and can sound more literary, poetic, or stylistically marked.

So for a learner, Её голос ровный и спокойный is the best standard pattern.

Yes. In normal modern Russian writing, you may see both её and ее, but the standard pronunciation is the same:

• её = pronounced roughly yi-YO

The stress is on the second syllable.

A few stress notes for the whole sentence:

• её → stress on -ё
• го́лос → stress on the first syllable
• ро́вный → stress on the first syllable
• споко́йный → stress on -кой-

So roughly:

• yi-YO GO-los ROV-nyy ee spa-KOY-nyy

Using ё in writing is often helpful for learners because it shows the stress clearly.

Yes. In dictionary form, many Russian masculine singular adjectives end in:

• -ый
• -ий
• sometimes -ой

Here both adjectives are in the masculine singular nominative form:

• ровный
• спокойный

That is the form you use because they agree with голос.

If the noun changed, the adjective endings would change too:

• спокойная речь
• спокойное лицо
• спокойные слова

and:

• ровная линия
• ровное дыхание
• ровные движения

In this exact present-tense sentence, the normal form is:

• Её голос ровный и спокойный.

That is the standard short linking pattern with omitted is.

You often see the instrumental after forms like был / будет / стал / является:

• Её голос был ровным и спокойным. = Her voice was steady and calm.
• Её голос стал ровным и спокойным. = Her voice became steady and calm.

So for the sentence you gave, ровный и спокойный is the right choice.

It means Her voice is steady and calm, so it describes the voice itself, not the action of speaking.

That is different from an adverbial sentence like:

• Она говорит спокойно. = She speaks calmly.

Compare:

• Её голос спокойный. = Her voice is calm.
• Она говорит спокойно. = She speaks calmly.

English sometimes blurs these ideas, but Russian keeps them structurally separate.

Yes. In fact, nouns ending in a hard consonant are very often masculine in Russian.

So:

• голос is masculine
• nominative singular: голос
• that is why the adjectives are ровный and спокойный

This is one of the most common gender patterns in Russian:

• consonant ending → often masculine
• -а / -я → often feminine
• -о / -е → often neuter

Of course there are exceptions, but голос follows the normal masculine pattern.