Музыка привлекла людей.

Because the subject is музыка, which is a feminine singular noun.

In the past tense, Russian verbs agree with the subject in gender and number:

• masculine: привлёк
• feminine: привлекла
• neuter: привлекло
• plural: привлекли

So Музыка привлекла людей literally has a feminine past-tense verb because музыка is feminine.

Музыка is in the nominative case, because it is the subject of the sentence — the thing doing the action.

So in this sentence:

• музыка = the music / music → subject, nominative
• привлекла = attracted
• людей = people → object

Because людей is the form used here for the direct object.

The basic dictionary form is люди (people), but in this sentence people are being attracted, so the noun is in the accusative case.

For animate plural nouns in Russian, the accusative usually looks like the genitive plural. That is why:

• nominative plural: люди
• accusative plural: людей

So Музыка привлекла людей means Music attracted people, with людей as the object.

You know from the verb and the sentence structure.

The verb привлечь / привлекать takes a direct object: attract someone/something. So in this sentence, людей is functioning as the object of the verb, which means it is accusative.

It just happens that for animate plural nouns, accusative plural = genitive plural in form.

So:

• form: людей
• function here: accusative plural

The infinitive is привлечь.

This is the perfective verb, meaning it presents the action as a completed whole: attracted, drew, managed to attract.

Its imperfective partner is привлекать.

So you can compare:

• Музыка привлекала людей. = The music was attracting people / used to attract people.
• Музыка привлекла людей. = The music attracted people.

Because Russian verbs agree with the subject, not the object.

Here:

• subject: музыка → singular feminine
• object: людей → plural

So the verb must be singular feminine: привлекла.

English works the same way in this respect:

• Music attracts people
• not Music attract people

Russian has no articles like a, an, or the, so the sentence can be interpreted in different ways depending on context.

Музыка привлекла людей could mean:

• Music attracted people
• The music attracted people
• The music attracted the people

In many contexts, the most natural translation is simply Music attracted people or The music attracted people.

Yes. Russian word order is more flexible than English because the cases show the roles of the words.

For example:

• Музыка привлекла людей.
• Людей привлекла музыка.

Both mean roughly the same thing, but the emphasis changes.

• Музыка привлекла людей = neutral order
• Людей привлекла музыка = puts more focus on people or contrasts them with something else

Even if the order changes, музыка is still the subject and людей is still the object.

It could be either, depending on context.

Russian often uses bare nouns without extra markers, so музыка may mean:

• music in general
• some music at an event
• a specific performance or musical sound

Context tells you which one is intended.

A careful pronunciation would be:

Му́зыка привлекла́ люде́й.

Stress:

• Му́зыка
• привлекла́
• люде́й

A rough English-style guide:

MOO-zy-ka priv-lee-KLA lyu-DYEY

This is only approximate, but it can help you hear where the stress falls.

Yes, but that changes the tense.

• Музыка привлекла людей = Music attracted people / The music attracted people
  past, completed event

• Музыка привлекает людей = Music attracts people
  present, general fact or current situation

So the original sentence is specifically in the past tense.

A very literal breakdown is:

• Музыка = music
• привлекла = attracted
• людей = people

So literally:

Music attracted people.

That is also a perfectly natural English translation in this case.