Många människor volonterar idag.

Because många already works as a determiner, like many in English. In Swedish, after words like många (many), få (few), några (some), and alla (all), you normally do not add an article.

So:

• många människor = many people
• not många en människor or anything similar

This is very similar to English, where you say many people, not many the people.

The word is:

• en människa = a person / a human being
• människor = people / human beings

So in this sentence, människor is the plural form because många requires a plural noun.

Literally, it means many people.

A word-by-word breakdown:

• många = many
• människor = people

It is a very normal Swedish noun phrase.

Volonterar is a present-tense verb form, so it means something like volunteer / are volunteering depending on context.

If treated as a regular -ar verb, the pattern would be:

• infinitive: volontera
• present: volonterar
• past: volonterade
• supine: volonterat

So in the sentence, Många människor volonterar idag, the meaning is Many people volunteer today or possibly Many people are volunteering today.

It is understandable, but it is not the most natural choice in all contexts.

Many Swedish speakers would more often say things like:

• Många människor jobbar som volontärer idag.
• Många människor volontärarbetar idag.
• Många människor arbetar ideellt idag.

The best alternative depends on the exact meaning:

• jobbar som volontärer = work as volunteers
• volontärarbetar = do volunteer work
• arbetar ideellt = work unpaid / do nonprofit volunteer work

So the sentence is understandable, but some learners should know that volonterar may sound less standard or less idiomatic than other options.

Because this is a normal Swedish main-clause word order:

• subject: Många människor
• verb: volonterar
• time expression: idag

So the sentence has a neutral structure:

Många människor volonterar idag.

Swedish often puts time expressions like idag near the end in simple statements.

But you can also move it to the front for emphasis:

Idag volonterar många människor.

When you do that, Swedish keeps the verb in the second position.

It can mean both, depending on context.

• today = on this day
• nowadays = in the present time / these days

So Många människor volonterar idag could mean:

• Many people are volunteering today
• or, in a broader context, Many people volunteer nowadays

Usually the surrounding context tells you which meaning is intended.

Because volonterar is already the main verb.

In English, learners sometimes expect an extra to be because of forms like are volunteering. But Swedish often uses the simple present where English may use either simple present or present progressive.

So:

• Många människor volonterar idag = Many people volunteer today / Many people are volunteering today

You would use är only if the sentence had a noun or adjective after it, for example:

• Många människor är volontärer idag. = Many people are volunteers today.

That sentence is different: it describes what they are, not what they do.

The basic order is:

Subject + Verb + Adverbial

Here that gives:

• Många människor = subject
• volonterar = verb
• idag = time adverbial

This is a standard Swedish main clause.

A very important rule in Swedish is verb-second word order in main clauses. That means the finite verb usually comes in the second position. So if you move idag to the front, the verb still stays second:

• Idag volonterar många människor.

Not:

• Idag många människor volonterar.

Yes. Both idag and i dag are accepted in Swedish.

• idag
• i dag

The one-word spelling idag is very common in modern Swedish, so the sentence looks completely normal as written.

A rough pronunciation guide is:

MONG-a MEN-ni-skor vo-lon-TE-rar ee-DAH

Very roughly, word by word:

• Många ≈ MONG-a
• människor ≈ MEN-ni-skor
• volonterar ≈ vo-lon-TE-rar
• idag ≈ ee-DAH

A few notes:

• å sounds roughly like the vowel in British more, but not exactly.
• ä is more open, somewhat like the vowel in bed.
• The stress in idag is on the second syllable.
• Since volonterar is not the most established everyday verb, pronunciation may vary a bit more than with very common verbs.