Спокойный голос учителя придаёт мне уверенности.

A very literal breakdown is:

• спокойный = calm
• голос = voice
• учителя = of the teacher / the teacher’s
• придаёт = gives, adds, imparts
• мне = to me
• уверенности = confidence

So the structure is basically:

[The] calm voice of the teacher gives me confidence.

Russian does not need articles like the or a, so those are understood from context.

It describes голос.

You can tell because спокойный is:

• masculine
• singular
• nominative

and it agrees with голос, which is also masculine singular nominative.

So:

• спокойный голос учителя = the teacher’s calm voice

If you wanted to say the voice of the calm teacher, you would say:

• голос спокойного учителя

There, спокойного agrees with учителя, not голос.

Because it is the masculine singular nominative form of the adjective.

It agrees with голос, which is:

• masculine
• singular
• nominative

In Russian, adjectives usually match the noun they describe in:

• gender
• number
• case

So:

• спокойный голос = calm voice
• спокойная речь = calm speech
• спокойное лицо = calm face
• спокойные слова = calm words

Here учителя is genitive singular: of the teacher.

It depends on голос:

• голос учителя = the teacher’s voice / the voice of the teacher

This is a very common Russian way to show possession.

Why is it not teachers? Because учителя can also be the nominative plural form in writing. The difference is usually:

• учИтеля = of the teacher (genitive singular)
• учителЯ = teachers (nominative plural)

In normal Russian spelling, stress marks are not written, so you use context to tell them apart. In this sentence, voice of the teacher makes clear sense.

придаёт is the 3rd person singular present tense form of придавать.

Here it means something like:

• gives
• adds
• lends
• imparts

So придаёт мне уверенности means roughly:

• gives me confidence
• makes me feel more confident

Because the subject is голос (voice), the verb is singular:

• голос придаёт = the voice gives

Also, the letter ё matters in pronunciation:

• written carefully: придаёт
• often written in ordinary text as придает
• but still pronounced pri-da-YOT

Because мне is the person receiving the effect.

With придавать / придать, Russian often uses:

• кому? = to whom?

So:

• мне = to me
• тебе = to you
• ему = to him
• нам = to us

In this sentence:

• голос учителя придаёт мне уверенности
• literally: the teacher’s voice gives to me confidence

English usually just says gives me confidence, but Russian marks that role with the dative.

This is a very good question, because learners often expect уверенность here.

In this sentence, уверенности is genitive singular. It gives a kind of partitive / indefinite amount nuance:

• gives me some confidence
• adds confidence
• gives me more confidence

With abstract nouns, Russian sometimes uses the genitive this way after verbs that mean add, give, or increase something.

So:

• придаёт мне уверенности = gives me confidence / makes me more confident

You may also hear:

• придаёт мне уверенность

That version is also understandable and natural. The genitive version often sounds a bit more like adds confidence rather than gives confidence as a full object.

So as a learner, you should recognize both, but the sentence you were given is idiomatic.

Yes. Russian word order is fairly flexible because the case endings show each word’s role.

The given order is natural and neutral:

• Спокойный голос учителя придаёт мне уверенности.

But you could also say:

• Мне придаёт уверенности спокойный голос учителя.
• Уверенности мне придаёт спокойный голос учителя.

These versions change the emphasis, not the core meaning.

Very roughly:

• sentence-first Спокойный голос учителя = emphasizes the subject first
• sentence-first Мне = emphasizes to me
• sentence-first Уверенности = emphasizes the effect, confidence

A stress-marked version is:

СпокОйный гОлос учИтеля придаЁт мне увЕренности.

Helpful notes:

• спокОйный
• гОлос
• учИтеля = of the teacher
• придаЁт = stress on ё
• мне
• увЕренности

A rough English-style approximation would be:

spa-KOY-ny goo-lus oo-CHEE-ti-lya pree-da-YOT mnye oo-VYE-ren-na-stee

Not exact, of course, but useful as a first guide.