Hiện tôi sống ở thành phố.

Hiện means currently, at present, or now. It tells you the time frame for the whole sentence.

So Hiện tôi sống ở thành phố means something like:

• Currently, I live in the city
• At present, I live in the city

You will also often see hiện nay or hiện tại, which are a little fuller and often more common in everyday explanations.

Vietnamese often puts time words or time phrases near the beginning to set the context first.

So:

• Hiện tôi sống ở thành phố = Currently, I live in the city
• Tôi hiện sống ở thành phố = also possible, and means basically the same thing

Putting hiện first is a natural way to frame the whole statement from the start.

It can mean both, depending on context.

Here, because it is followed by a location phrase ở thành phố, it clearly means to live/reside.

• sống = to live
• sống ở... = to live in/at...

So in this sentence, tôi sống ở thành phố means I live in the city, not I am alive in the city.

Here ở marks location. After sống, it means in or at.

• sống ở thành phố = live in the city
• sống ở Hà Nội = live in Hanoi
• sống ở Việt Nam = live in Vietnam

So ở is doing the job that English prepositions like in or at would do.

Vietnamese does not use articles like English a, an, and the.

That means thành phố can be understood from context as:

• the city
• a city
• sometimes urban areas / the city in contrast with the countryside

In this sentence, English might translate it as the city, but Vietnamese does not need a separate word for the.

Because no classifier is needed here.

In this sentence, thành phố is just the noun used as the object of the preposition ở. Vietnamese classifiers are more relevant in certain structures, especially when counting or specifying nouns.

For example:

• một thành phố = a city
• hai thành phố = two cities

But in ở thành phố, you can simply use the noun directly.

Yes, you could.

• Tôi sống ở thành phố = I live in the city
  This is a general statement about where you live.
• Tôi đang sống ở thành phố = I am currently living in the city
  This can sound more temporary or more focused on the present situation.

So đang adds a stronger sense of currently in progress / for now. Without đang, the sentence is more neutral and general.

Yes, it is grammatical and understandable.

However, depending on context, a Vietnamese speaker might also say:

• Hiện tại tôi sống ở thành phố.
• Bây giờ tôi sống ở thành phố.
• Tôi hiện sống ở thành phố.

Also, thành phố by itself is a bit general. If you mean a specific place, it is often more natural to name it:

• Hiện tôi sống ở Hà Nội.
• Hiện tôi sống ở Thành phố Hồ Chí Minh.

If you mean in a city rather than in the city, you might say:

• Hiện tôi sống ở một thành phố.

It depends on context.

By itself, ở thành phố often suggests in the city / in an urban area, especially in contrast with ở nông thôn or ở quê.

So this sentence can feel like:

• I currently live in the city
  rather than
• I currently live in a particular named city

If you want to be specific, you would usually name the city.

A rough breakdown is:

• Hiện — falling, heavy tone
• tôi — level tone
• sống — rising tone
• ở — dipping tone
• thành — low falling tone
• phố — rising tone

A rough English-style approximation is:

hee-en toy sohng uh thanh foh

But that is only approximate. The tones are very important in Vietnamese, so it is best to learn them from audio if possible.