Questo passaggio è stretto.

Because passaggio is a masculine singular noun in Italian, so the demonstrative must match it.

• questo = this (masculine singular)
• questa = this (feminine singular)

So:

• questo passaggio = this passage / this passageway
• questa strada = this street

Italian demonstratives agree in gender and number with the noun they describe.

Passaggio can mean several related things depending on context, such as:

• passage
• passageway
• corridor
• way through
• sometimes even crossing or transition

In Questo passaggio è stretto, it most naturally means a physical passageway or narrow space you go through.

The accent is important because è and e are different words in Italian:

• è = is
• e = and

So in this sentence:

• Questo passaggio è stretto = This passage is narrow

Without the accent, it would be the word and, which would be incorrect here.

Because stretto is being used as a predicate adjective after the verb essere (to be).

The structure is:

• Questo passaggio = subject
• è = is
• stretto = narrow

This is very similar to English:

• This passage is narrow

Italian adjectives can appear after a noun when directly describing it, or after a verb like essere when they are part of the predicate.

Compare:

• un passaggio stretto = a narrow passage
• il passaggio è stretto = the passage is narrow

Because stretto must agree with passaggio, which is masculine singular.

Agreement pattern:

• stretto = masculine singular
• stretta = feminine singular
• stretti = masculine plural
• strette = feminine plural

Examples:

• Questo passaggio è stretto = This passage is narrow
• Questa strada è stretta = This street is narrow
• Questi passaggi sono stretti = These passages are narrow

Yes, but it means something slightly different in structure.

• Questo passaggio è stretto = This passage is narrow.
• Questo è un passaggio stretto = This is a narrow passage.

The first sentence talks about a specific passage and describes it.
The second identifies this thing as a narrow passage.

Both are correct, but they are not used in exactly the same way.

No. Stretto can be used both literally and figuratively.

Literal:

• una strada stretta = a narrow road
• un passaggio stretto = a narrow passage

Figurative or extended uses:

• in senso stretto = in the strict/narrow sense
• essere a stretto contatto = to be in close contact
• tempi stretti = tight deadlines / limited time

In your sentence, it is clearly the literal physical meaning: narrow.

Yes. That would mean:

• Il passaggio è stretto = The passage is narrow

The difference is:

• questo passaggio = this passage
• il passaggio = the passage

Use questo when you want to point out this specific one, especially something near you or already being indicated.

A simple pronunciation guide is:

KWE-stoh pas-SAJ-joh eh STRET-toh

A few details:

• qu in questo sounds like kw
• gg in passaggio sounds like the dg in bridge
• è is pronounced like eh
• tt in stretto is a doubled consonant, so it is pronounced more distinctly than a single t

If you want to sound more natural, stress these syllables:

• QUÉ-sto
• pas-SÀG-gio
• È
• STRÉT-to

Sometimes, yes, but they are not identical.

• stretto is the common everyday word for narrow
• angusto also means narrow/cramped, but it is usually more formal or literary

So:

• Questo passaggio è stretto sounds natural and standard
• Questo passaggio è angusto is possible, but less everyday and may suggest cramped or confined

For a normal learner sentence, stretto is the best choice.