فيه ناس كتير في الدنيا.

Yes. In this sentence, فيه is the Egyptian Arabic way to say there is or there are.

So:

• فيه ناس كتير = There are many people

Even though فيه literally looks like in it in other contexts, here it functions as an existential expression: it introduces the existence of something, just like English there is / there are.

In Egyptian Arabic, فيه is used with both singular and plural nouns:

• فيه مشكلة = There is a problem
• فيه ناس = There are people

So Arabic does not switch between two forms the way English does with is/are.

Because the two في forms are doing different jobs.

1. فيه at the beginning means there is / there are
2. في الدنيا means in the world

So:

• فيه = there is / there are
• في الدنيا = in the world

This is very common in Egyptian Arabic, and native speakers do not find it repetitive.

ناس means people. It refers to more than one person, so in meaning it is plural/collective.

A useful way to think of it is:

• ناس = people

Unlike English, where people has a related singular person, Arabic ناس is a separate word and does not work like a normal broken plural that you can easily reverse into a singular form.

If you want to refer to one person in everyday Egyptian Arabic, you would usually use something else, such as:

• واحد = one person / someone
• شخص = person
• بني آدم = human being / person

So in this sentence, ناس simply means people.

In Egyptian Arabic, كتير often comes after the noun when it means many / a lot of.

So:

• ناس كتير = many people / a lot of people

This word order is very natural in Arabic. English says:

• many people

But Egyptian Arabic usually says:

• people many

You will see this pattern a lot:

• فلوس كتير = a lot of money
• أصحاب كتير = many friends
• حاجات كتير = many things

So although it feels reversed from English, it is the normal Arabic structure.

No, not in this use.

In ناس كتير, كتير means many / a lot and stays the same. It does not change here to match the noun the way some adjectives do.

So you can learn this chunk very comfortably as:

• noun + كتير = many/a lot of + noun

Examples:

• شغل كتير = a lot of work
• أسئلة كتير = many questions
• بنات كتير = many girls

Yes, الدنيا literally means the world, but in Egyptian Arabic it can also carry the broader sense of:

• the world
• life
• this world
• the world around us

In في الدنيا, the meaning is simply in the world.

You may notice that it has الـ at the beginning:

• الدنيا = the world

That is normal. Arabic often says the world where English may simply say the world too, so this part matches quite nicely.

A natural pronunciation would be something like:

fīh nās kitīr fid-dunyā

A few notes:

• فيه = fīh
• ناس = nās
• كتير = kitīr
• في الدنيا often sounds like fid-dunyā, because the words run together in speech

The ال in الدنيا is pronounced clearly here because د is not a sun letter. So it stays ad-/id- rather than assimilating.

Because Arabic often does not need a separate verb like is/are in this kind of structure.

In English, you must say:

• There are many people in the world

In Egyptian Arabic, the existential word فيه already does that job, so no extra verb is needed.

This is completely normal and very common.

Yes, but the wording would usually be a little different.

The Egyptian sentence is:

• فيه ناس كتير في الدنيا

A more Modern Standard Arabic version might be:

• هناك ناس كثيرون في العالم
• or يوجد الكثير من الناس في العالم

Differences you may notice:

• Egyptian uses فيه very naturally for there is/there are
• Egyptian uses ناس كتير
• MSA often prefers forms like كثيرون or الكثير من الناس
• Egyptian says الدنيا very naturally in speech, while MSA often uses العالم for the world

So the original sentence is very colloquial and natural in Egyptian Arabic.

Yes. In fast everyday speech, some speakers may pronounce it more like fī than fīh, especially depending on region, speed, and personal style.

So you may hear:

• fī nās kitīr fid-dunyā

and also:

• fīh nās kitīr fid-dunyā

Both are normal in speech. For learning, it is useful to recognize both.

It can mean either one.

• many people
• a lot of people

In natural English translation, either works depending on tone.

So:

• فيه ناس كتير في الدنيا
  can be understood as
• There are many people in the world
• There are a lot of people in the world

The Arabic expression itself is very natural and neutral.

ناس here is indefinite: it means people in a general sense, not the people.

That is why it does not have الـ.

Compare:

• ناس كتير = many people
• الناس = the people / people in general

In existential sentences with فيه, Arabic often introduces something indefinite:

• فيه ولد برا = There is a boy outside
• فيه مشكلة = There is a problem
• فيه ناس كتير = There are many people

So ناس without الـ is exactly what you would expect here.

It can be both.

Literally, it means:

• There are many people in the world

But depending on context, it can also imply a broader idea such as:

• there are all kinds of people out there
• the world is full of people
• you are not alone / there are plenty of others

So while the sentence is simple, it can carry a general life observation too, depending on how it is used.