В салоне самолёта было тихо, и через иллюминатор было видно море.

Because салон самолёта means the cabin/interior of the airplane.

Russian often uses the pattern:

• X + genitive noun = X of Y

So:

• салон = cabin/interior
• самолёта = of the airplane

That gives в салоне самолёта = in the airplane cabin.

Not really. In this sentence, салон means the passenger cabin/interior of a vehicle, especially a plane.

So в салоне самолёта means:

• in the cabin of the airplane
• inside the passenger area of the plane

It does not mean a beauty salon here.

Because тихо by itself means quiet(ly), but in Russian it can also act as a predicative word meaning it is/was quiet.

So:

• тихо = quiet
• было тихо = it was quiet

Russian often uses было in the past tense with words like:

• тихо = quiet
• холодно = cold
• темно = dark
• жарко = hot

This is an impersonal construction: there is no real subject like it in English, but English usually translates it with it was ....

Because this is an impersonal sentence.

In Russian, impersonal past-tense constructions usually use the neuter singular form:

• было

So:

• было тихо = it was quiet
• было видно = it was visible / one could see

There is no grammatical subject here that would force masculine or feminine agreement.

It looks like an adverb, and historically it is related to one, but in this sentence it functions more like a predicative state word:

• В салоне самолёта было тихо. = It was quiet in the airplane cabin.

So it is not modifying a verb like speak quietly. Instead, it describes the state of the environment.

Compare:

• Он говорил тихо. = He spoke quietly.
  Here тихо is a regular adverb.

• В комнате было тихо. = The room was quiet / It was quiet in the room.
  Here it describes a state.

This is another impersonal construction.

• видно means visible / can be seen
• было видно = was visible / could be seen

So:

• через иллюминатор было видно море
  = through the window, the sea could be seen

A very natural English translation is:

• you could see the sea through the window
• the sea was visible through the window

Russian often uses this structure instead of a personal sentence like мы видели море.

Yes, it is related to видеть (to see), but here видно is not a normal finite verb form like вижу or видел.

In this sentence, видно is a predicative word meaning:

• visible
• can be seen

So:

• море видно = the sea is visible
• было видно море = the sea was visible / one could see the sea

It is a very common Russian pattern.

Иллюминатор is a more specific word. It means a porthole or the small window in a plane or ship.

So:

• окно = window (general word)
• иллюминатор = airplane/ship window, porthole-like opening

In an airplane context, иллюминатор sounds more natural and precise.

The preposition через normally takes the accusative case and often means:

• through
• across

So:

• иллюминатор → accusative singular: иллюминатор
  (same form as nominative for this masculine inanimate noun)

That is why we get:

• через иллюминатор = through the window

In practical terms, море is the thing being seen: the sea.

For learners, the important point is that море has the same form in the nominative and accusative singular:

• nominative: море
• accusative: море

So the form itself does not show a difference here.

You can understand the whole phrase as:

• было видно море = the sea was visible / one could see the sea

That is the main thing to recognize.

Russian word order is flexible, and this version sounds natural because it presents the scene in a smooth order:

1. where/from where — через иллюминатор
2. state — было видно
3. what — море

Ending with море gives it a nice informational focus: first the sentence sets up the viewing point, then reveals what was visible.

Other word orders are possible, for example:

• Море было видно через иллюминатор.

This is also correct, but the emphasis is a little different.

Because и is joining two separate clauses, each with its own predicate:

1. В салоне самолёта было тихо
2. через иллюминатор было видно море

Since these are two independent clauses, Russian normally uses a comma before и.

Yes, but that would change the tense.

• В салоне самолёта тихо. = It is quiet in the airplane cabin.
  Present tense

• В салоне самолёта было тихо. = It was quiet in the airplane cabin.
  Past tense

In the present tense, Russian often has no verb equivalent to English is in this kind of sentence. In the past tense, you need было.

Yes, ё shows the pronunciation clearly:

• самолёт = airplane
• genitive singular: самолёта

In many printed texts, Russians often write е instead of ё, so you may also see:

• самолета

But the correct pronunciation is still with yo: samalyota.

For learners, it is helpful to remember the dictionary form with ё:

• самолёт