В комнате чувствуется запах кофе.

Here чувствуется means something like is felt / can be sensed / is noticeable.

The ending -ся often makes a verb reflexive, but in sentences like this it often gives a passive-like or impersonal sense. So instead of someone smells the coffee, Russian says something closer to:

The smell of coffee is felt in the room.

That is why чувствуется works well here: it describes a sensation that is present, without naming the person who notices it.

Grammatically, запах is the subject.

You can tell because:

• it is in the nominative case
• the verb is singular, agreeing with запах

So structurally, the sentence is not fully impersonal in the strict grammatical sense. It has a subject: запах кофе.

However, semantically it feels a bit impersonal to an English speaker, because Russian does not mention who is sensing the smell. The idea is simply that the smell is noticeable.

Because в plus the prepositional case is used for location: in the room.

• комната = room
• в комнате = in the room

This is a static location, not movement.

Compare:

• в комнате = in the room
• в комнату = into the room

So here в комнате answers where?

After запах Russian normally uses the genitive to show what the smell is a smell of.

So:

• запах кофе = smell of coffee
• запах хлеба = smell of bread
• запах дыма = smell of smoke

The reason кофе does not visibly change is that кофе is an indeclinable noun in standard Russian. Its form stays the same in different cases.

So even though it still looks like кофе, in this sentence it is functioning as genitive after запах.

Because the grammatical subject is singular:

• запах = smell

So the verb agrees with it:

• запах чувствуется = the smell is noticeable

If the subject were plural, the verb would also be plural:

• В комнате чувствуются запахи кофе и табака. = The smells of coffee and tobacco are noticeable in the room.

Yes, absolutely. That is very natural Russian.

• В комнате пахнет кофе = It smells like coffee in the room / The room smells of coffee.
• В комнате чувствуется запах кофе = The smell of coffee is noticeable in the room.

The difference is mainly in style and focus:

• пахнет кофе is simpler and very common in everyday speech
• чувствуется запах кофе is a bit more descriptive and slightly more formal or literary

The second version focuses more on the smell itself as a thing being perceived.

No, Russian word order is fairly flexible, but different orders change the emphasis.

The version you have:

• В комнате чувствуется запах кофе.

is a very natural, neutral way to present the scene: first the place, then what is noticeable there.

You could also say:

• Запах кофе чувствуется в комнате.

This puts more emphasis on запах кофе.

Or:

• Чувствуется запах кофе в комнате.

This is possible, but less neutral in everyday use.

So the word order is not fixed, but the original sentence sounds very natural and balanced.

Because this sentence is not just saying that the smell exists. It is saying that the smell is perceptible.

Russian often avoids есть when another more meaningful predicate is available. Here, чувствуется gives much more information than есть would.

• В комнате чувствуется запах кофе = The smell of coffee is noticeable in the room.
• В комнате есть запах кофе sounds unnatural in most contexts.

If you want to talk about what the room smells like, Russian prefers verbs such as:

• пахнет
• чувствуется

rather than есть.

Not necessarily.

Запах is a neutral word meaning smell / odor. It can be pleasant, unpleasant, or neutral depending on context.

If you want to emphasize that it is a pleasant smell, Russian often uses аромат:

• аромат кофе = aroma of coffee

So:

• В комнате чувствуется запах кофе = neutral
• В комнате чувствуется аромат кофе = more clearly pleasant, and a bit more expressive

A very literal translation would be:

In the room, the smell of coffee is felt.

That sounds unnatural in English, so a more natural English version would be:

• There is a smell of coffee in the room
• The smell of coffee can be sensed in the room
• The room smells of coffee
  depending on context

This is a good example of Russian expressing something in a way that is grammatically different from natural English, even though the meaning is simple.