Milion ljudi igra.

Because the grammatical subject here is milion (a million), not ljudi by itself.

In Serbian, words like milion, hiljada, and stotina behave like nouns. The verb often agrees with that noun, so:

• Milion ljudi igra. = literally, A million of people plays/is playing
• so the verb is 3rd person singular: igra

This can feel strange to an English speaker, because English usually agrees with people semantically. In Serbian, singular agreement here is normal and standard.

You may sometimes hear plural agreement in less careful or more meaning-based speech, but for learning purposes, Milion ljudi igra is the safe and correct model.

Because after milion, the counted noun normally appears in the genitive plural.

So:

• milion ljudi = a million people
• milion knjiga = a million books
• milion automobila = a million cars

The word ljudi is the genitive plural form used here, and it is also the regular plural form of čovek in many contexts involving people.

So the pattern is:

• milion + genitive plural noun

No. The basic dictionary form is usually čovek (person, man) or sometimes ljudi is learned as the plural meaning people.

This is an irregular noun pair:

• singular: čovek = person / man
• plural: ljudi = people

So ljudi does not come from a singular ljud. It is an irregular plural form and one of the words you simply need to memorize.

Because Serbian has no articles.

English uses:

• a million people
• the million people

Serbian does not have words like a/an/the, so it simply says:

• Milion ljudi

The meaning of definiteness or indefiniteness usually comes from context.

It can mean either, depending on context.

The verb igrati is broad and can mean:

• to play
• to dance

So Milion ljudi igra could mean:

• A million people are playing
• A million people are dancing

Without more context, the sentence is ambiguous. Serbian often leaves that to the situation.

The infinitive is igrati.

Here is the present tense:

• ja igram = I play / am playing
• ti igraš
• on/ona/ono igra
• mi igramo
• vi igrate
• oni/one/ona igraju

In Milion ljudi igra, the form igra is 3rd person singular present.

You may hear that in speech, because speakers sometimes make the verb agree with the meaning (people) rather than the grammatical head (milion).

However, the standard beginner-friendly form is:

• Milion ljudi igra.

So if you are learning the rule, use singular agreement after milion:

• Milion ljudi igra
• Hiljada ljudi peva
• Stotinu ljudi čeka

That is the pattern you should rely on.

Yes, you can.

Serbian word order is more flexible than English. Both of these are possible:

• Milion ljudi igra.
• Igra milion ljudi.

The first one is the most neutral if you are simply stating a fact.

The second one may sound more like you are presenting the action first, or answering a question such as Who is playing/dancing?

So:

• Milion ljudi igra. = neutral
• Igra milion ljudi. = same basic meaning, different focus

Yes, but usually milion ljudi is more natural.

• milion ljudi = normal, neutral
• jedan milion ljudi = more emphatic, more precise-sounding, or stylistically heavier

English often says one million for emphasis. Serbian can do the same with jedan milion, but in ordinary usage milion alone is enough.

In Serbian grammar, milion behaves largely like a noun.

That is why:

• it can decline like a noun
• the following noun goes into the genitive plural
• the verb can agree with milion in the singular

For example:

• nominative: milion
• genitive: miliona

So in many grammatical explanations, milion is treated more like a counting noun than like a simple numeral.

Yes:

• Milion osoba igra.

This is grammatically fine, but it sounds more formal or administrative.

Compare:

• milion ljudi = more natural in everyday language
• milion osoba = more formal, official, statistical

So in ordinary speech, ljudi is usually the more idiomatic choice.

Because milion is in the nominative singular, since it is the subject of the sentence.

The structure is:

• Milion = nominative singular subject
• ljudi = genitive plural after milion
• igra = 3rd person singular verb agreeing with milion

If the sentence required another case, milion would change. For example:

• bez miliona ljudi = without a million people (genitive)

So the form milion here is simply the nominative form.

You know from context.

The present tense in Serbian can mean:

• a general fact/habit
• something happening now

So Milion ljudi igra could mean:

• A million people play
• A million people are playing

Serbian, like many languages, often uses the same present-tense form for both. Context tells you which meaning is intended.