Sperrebåndet er rødt.

Because Norwegian usually adds the definite article to the end of the noun.

• et sperrebånd = a barrier tape / a cordon tape
• sperrebåndet = the barrier tape

The ending -et shows that the noun is:

• singular
• definite
• neuter gender

So sperrebåndet literally means the barrier tape.

In Norwegian, the is often built into the noun instead of standing in front of it.

Compare:

• English: the tape
• Norwegian: båndet

This is very normal in Norwegian. So in Sperrebåndet er rødt, the word sperrebåndet already includes the.

The dictionary form is sperrebånd.

It is a compound noun:

• sperre = barrier, blockade, cordon
• bånd = tape, band, strip

Together, sperrebånd means something like barrier tape, cordon tape, or in some contexts police tape.

Sperrebånd is a neuter noun.

That matters because gender affects:

• the indefinite article
• the definite ending
• adjective agreement

Forms:

• et sperrebånd = a barrier tape
• sperrebåndet = the barrier tape

Because it is neuter, the adjective in this sentence becomes rødt, not rød.

Because the adjective has to agree with the noun.

Here, sperrebåndet is:

• singular
• definite
• neuter

When rød is used as a predicate adjective after er, the neuter singular form is rødt.

Compare:

• Bilen er rød. = The car is red.
  (bil is common gender)
• Huset er rødt. = The house is red.
  (hus is neuter)
• Sperrebåndet er rødt. = The barrier tape is red.

It can do both, but the form depends on the grammar.

Before a neuter singular noun:

• et rødt bånd = a red tape/band

After er with a neuter singular subject:

• Båndet er rødt. = The tape/band is red.

So rødt is not special to this sentence; it is the normal neuter singular form of rød.

Er means is / are / am depending on context. It is the present tense of å være = to be.

Examples:

• jeg er = I am
• du er = you are
• han er = he is
• de er = they are

Unlike English, Norwegian uses the same present-tense form er for all persons.

No, this is a very standard Norwegian sentence pattern:

• Subject + verb + complement

So:

• Sperrebåndet = subject
• er = verb
• rødt = complement/adjective

This is the normal order for a simple statement:

• Bilen er stor. = The car is big.
• Huset er gammelt. = The house is old.
• Sperrebåndet er rødt. = The barrier tape is red.

A rough guide for an English speaker is:

• Sperrebåndet ≈ SPERR-eh-bon-det
• er ≈ air (but shorter, depending on dialect)
• rødt has the Norwegian ø, which does not exist in English

A few notes:

• å in bånd sounds roughly like the vowel in British law
• ø in rødt is a rounded front vowel; you may think of saying eh while rounding your lips
• the final t in rødt is pronounced

Pronunciation varies by dialect, but those points will help.

Yes, in the right context it can.

Sperrebånd is a general word for tape used to block off an area. Depending on the situation, English translations could include:

• barrier tape
• cordon tape
• warning tape
• police tape

So the exact English wording depends on what kind of tape is being talked about.