Robotstøvsugeren står i dokkingstasjonen.

Because -en is the definite article attached to the noun.

In English, you say the robot vacuum with a separate word, the.
In Norwegian, the definite article is usually added to the end of the noun:

• en robotstøvsuger = a robot vacuum
• robotstøvsugeren = the robot vacuum

So robotstøvsugeren means the robot vacuum.

Norwegian often marks definiteness by adding an ending to the noun instead of using a separate article.

So:

• dokkingstasjon = docking station
• dokkingstasjonen = the docking station

And:

• robotstøvsuger = robot vacuum
• robotstøvsugeren = the robot vacuum

That is why the sentence does not need a separate word like English the.

Yes. Norwegian very often combines nouns into one long word.

Here:

• robot = robot
• støvsuger = vacuum cleaner

Together:

• robotstøvsuger = robot vacuum / robot vacuum cleaner

Then the definite ending is added:

• robotstøvsugeren = the robot vacuum

This is extremely normal in Norwegian. English often writes similar ideas as two words, but Norwegian usually prefers one compound word.

This is a very common question. Norwegian often uses verbs like:

• står = stands
• ligger = lies
• sitter = sits

where English would often simply use is.

So Robotstøvsugeren står i dokkingstasjonen is literally something like:

• The robot vacuum stands in the docking station

but in natural English the meaning is simply:

• The robot vacuum is in the docking station

Norwegian uses stå for many things that are upright, positioned, or resting in a certain place. A robot vacuum in its dock is often described with står.

Yes, you probably could, and people would understand you. But it is less idiomatic in many contexts.

• er i focuses more on simple location: is in
• står i sounds more natural when describing where an object is positioned

So:

• Robotstøvsugeren står i dokkingstasjonen = more natural/idiomatic
• Robotstøvsugeren er i dokkingstasjonen = understandable, but less specific in tone

This kind of choice is very common in Norwegian.

Because i usually means in and på usually means on, though Norwegian usage is not always identical to English.

Here, the robot vacuum is understood as being in its docking station, so i is the natural choice:

• i dokkingstasjonen = in the docking station

If you said på, it would suggest a different spatial relationship, more like being on the docking station rather than docked in it.

The sentence follows the normal Norwegian main-clause order:

• Robotstøvsugeren = subject
• står = verb
• i dokkingstasjonen = prepositional phrase telling location

So the pattern is:

• Subject + Verb + Place

This is very similar to basic English word order:

• The robot vacuum + is/stands + in the docking station

A possible indefinite version would be:

• En robotstøvsuger står i en dokkingstasjon.

That means:

• A robot vacuum is standing in a docking station.

Compare:

• en robotstøvsuger = a robot vacuum
• robotstøvsugeren = the robot vacuum
• en dokkingstasjon = a docking station
• dokkingstasjonen = the docking station

So the original sentence is definite for both nouns.

In Bokmål, both of these are commonly treated as masculine nouns:

• en robotstøvsuger
• en dokkingstasjon

That is why the definite singular form ends in -en:

• robotstøvsugeren
• dokkingstasjonen

For a learner, the key thing is to memorize the noun together with its article when possible:

• en robotstøvsuger
• en dokkingstasjon

The plural forms would be:

For robotstøvsuger:

• en robotstøvsuger = a robot vacuum
• robotstøvsugeren = the robot vacuum
• robotstøvsugere = robot vacuums
• robotstøvsugerne = the robot vacuums

For dokkingstasjon:

• en dokkingstasjon = a docking station
• dokkingstasjonen = the docking station
• dokkingstasjoner = docking stations
• dokkingstasjonene = the docking stations

This is useful because once you know the pattern, many similar nouns become easier to recognize.

It is a Norwegian word in the sense that it is used in Norwegian, but it is clearly built from borrowed/international material.

• dokking comes from docking
• stasjon means station

Together, dokkingstasjon means docking station.

Norwegian often adopts technical terms like this and treats them like ordinary Norwegian nouns, giving them Norwegian endings:

• dokkingstasjon
• dokkingstasjonen
• dokkingstasjoner

A very literal breakdown is:

• Robotstøvsugeren = the robot vacuum
• står = stands
• i = in
• dokkingstasjonen = the docking station

So word-for-word:

• The robot vacuum stands in the docking station

But the most natural English meaning is simply:

• The robot vacuum is in the docking station.

That difference between literal wording and natural translation is very common when learning Norwegian.