Самолёт садится в аэропорту.

Самолёт is the nominative singular form, because it is the subject of the sentence — the thing doing the action.

• самолёт = plane / airplane
• singular, because it means one plane
• nominative, because it answers what is landing? → самолёт

If it were plural, you would get самолёты.

Садится is the 3rd person singular present tense of садиться.

So it literally means:

• he/she/it sits down
• and with things like planes, it means lands / is landing

Because самолёт is singular, the verb is also singular:

• самолёт садится = the plane is landing
• самолёты садятся = the planes are landing

The -ся ending is very common in Russian and often marks a reflexive or intransitive verb.

Here, садиться means something like to sit down or, for a plane, to land. The subject undergoes the action itself.

Compare:

• самолёт садится = the plane is landing
• пилот сажает самолёт = the pilot is landing the plane

So:

• садиться = the subject lands / sits down
• сажать / посадить = to seat, to place, to land something

That is why садится is used here, not a non-reflexive form.

Because в аэропорту means at/in the airport, describing the location where the landing happens.

Russian uses:

• в + accusative for motion toward / into
• в + prepositional (or locative) for location

Compare:

• Самолёт летит в аэропорт. = The plane is flying to the airport.
• Самолёт садится в аэропорту. = The plane is landing at the airport.

In this sentence, the important idea is not going into the airport building, but landing at that location, so в аэропорту is the natural choice.

This is a useful special case.

The noun аэропорт has a special locative-style form after в or на when it means physical location:

• в аэропорту = at the airport

This -у ending appears with some masculine nouns in fixed location expressions, for example:

• в саду = in the garden
• на полу = on the floor
• в шкафу = in the cupboard
• в аэропорту = at the airport

So although learners often expect в аэропорте, standard Russian normally says в аэропорту for location.

Russian does not have a separate form exactly like English is landing.

So садится can often be translated as:

• lands
• is landing

In this sentence, English usually prefers is landing, because it sounds like an action happening right now.

So grammatically it is present tense, but in English the most natural translation is often the present continuous.

Yes. Russian word order is fairly flexible, because case endings show grammatical roles.

The neutral order here is:

• Самолёт садится в аэропорту.

But you could also hear:

• В аэропорту садится самолёт.

That still means basically the same thing, but the emphasis changes:

• Самолёт садится в аэропорту. → neutral, starting with the plane
• В аэропорту садится самолёт. → emphasis on where it is happening

So word order in Russian often affects focus more than basic meaning.

Russian has no articles.

So самолёт can mean:

• a plane
• the plane

You understand which one is meant from context.

That is very normal in Russian. The sentence itself does not tell you whether the plane is definite or indefinite; English usually has to choose one.

The stress is:

• самолёт
• сади́тся
• в аэропорту́

A rough pronunciation guide:

• самолёт → sama-LYOT
• сади́тся → sa-DEET-sya
• в аэропорту́ → v a-ye-ra-par-TU

A few useful notes:

• ё is always stressed: самолёт
• in садится, the stress is on -ди́-
• in аэропорту́, the stress is on the final -у́

Yes. In real Russian writing, ё is often replaced by е, so you may see:

• самолёт
• самолет

They mean the same word. But the correct pronunciation is still with ё:

• самолёт

For learners, writing ё is very helpful because it shows the stress and the correct sound.

No. Its basic meaning is something like to sit down.

Examples:

• Он садится на стул. = He sits down on a chair.
• Самолёт садится. = The plane is landing.

So with people, it usually means sit down.
With planes and some other vehicles, it can mean land.

This kind of meaning extension is very common in Russian verbs.