Bagasjeoppbevaringen er stengt.

It is a compound noun:

• bagasje = luggage, baggage
• oppbevaring = storage, keeping
• -en = the definite ending

So bagasjeoppbevaringen literally means the luggage storage or the baggage storage.

The main part, grammatically, is oppbevaring, and bagasje tells you what kind of storage it is.

Because Norwegian normally writes compound nouns as one word.

So where English often writes:

• luggage storage
• train station
• summer holiday

Norwegian usually writes:

• bagasjeoppbevaring
• togstasjon
• sommerferie

This is very normal in Norwegian, even when the word gets long.

In Norwegian, the is often built into the noun as an ending.

So:

• bagasjeoppbevaring = luggage storage
• bagasjeoppbevaringen = the luggage storage

That -en at the end is doing the job that the does in English.

A separate word like den is usually added when there is also an adjective:

• den nye bagasjeoppbevaringen = the new luggage storage

The ending -en marks the definite singular form here.

The head noun is oppbevaring, which in Bokmål can be treated as feminine or as common-gender/masculine-style, depending on writing style. That means you may see:

• bagasjeoppbevaringen
• bagasjeoppbevaringa

Both can be correct in Bokmål, but -en is very common.

So this sentence uses a very standard Bokmål form.

Er is the present tense of å være, meaning to be.

So:

• er = is / are

In this sentence, it simply links the subject to its state:

• Bagasjeoppbevaringen er stengt = the luggage storage is closed

You can compare:

• var stengt = was closed
• skal være stengt = will be closed
• har vært stengt = has been closed

Stengt is the past participle of å stenge, which means to close or to shut.

Here it describes a state:

• er stengt = is closed

This is a very common expression for places, services, doors, offices, shops, and facilities:

• Butikken er stengt = the shop is closed
• Døren er stengt = the door is closed

Because after er, Norwegian very often uses the participle form stengt to describe the state, and that form commonly stays the same in this kind of sentence.

For example:

• Døren er stengt
• Butikken er stengt
• Butikkene er stengt

So even when the noun changes, stengt often does not.

If the word is used before a noun instead, other forms can appear:

• et stengt rom = a closed room
• stengte dører = closed doors

So the form in your sentence is completely normal.

Not quite in the same way English learners often think of passive.

Er stengt usually describes a state or result: the luggage storage is in a closed state.

If you want to emphasize the action or process of being closed, Norwegian often uses blir stengt:

• Bagasjeoppbevaringen blir stengt klokka 22 = the luggage storage is being closed / gets closed at 10 p.m.

So:

• er stengt = is closed, closed right now
• blir stengt = gets closed, is being closed

Yes, it is possible, but stengt is usually the more natural choice for a service, facility, shop, or office being closed.

Very roughly:

• stengt often fits opening hours, access, or availability
• lukket can sound more like physically shut or closed off

There is overlap, and both can be correct in some contexts, but for signs and public information, stengt is very common.

No, this is the normal main-clause order:

• Bagasjeoppbevaringen = subject
• er = finite verb
• stengt = complement

So it follows the basic pattern:

• Subject + verb + rest

Norwegian also has the usual main-clause rule that the finite verb comes in second position. For example:

• I dag er bagasjeoppbevaringen stengt = Today the luggage storage is closed

Here I dag comes first, and er still stays in second position.

You might see something like that in a short sign or headline, but in a full normal sentence, bagasjeoppbevaringen is more natural if you mean a specific luggage-storage facility.

Compare:

• Bagasjeoppbevaringen er stengt = the luggage storage is closed
• Bagasjeoppbevaring = luggage storage, the general idea or service

So the version with -en is the most natural full sentence when referring to the actual place or service at a station, airport, or similar location.