मोहल्ला शांत है।

A good learner-friendly pronunciation is:

mohallā shānt hai

Roughly:

• मोहल्ला → mo-HAL-laa
• शांत → shaant
• है → hai (similar to high)

A few notes:

• The ल्ल in मोहल्ला gives a doubled l sound.
• The ा gives a long aa sound.
• शांत is often said smoothly as shaant.

The sentence breaks down like this:

• मोहल्ला = the neighborhood / locality
  
  • this is the subject
• शांत = quiet / calm / peaceful
  
  • this is describing the subject
• है = is
  
  • this is the present-tense form of to be

So the structure is:

subject + description + है

Hindi normally does not use articles like a, an, and the.

So मोहल्ला शांत है can mean:

• The neighborhood is quiet
• A neighborhood is quiet

Usually the context tells you which one is meant. This is very normal in Hindi.

Because Hindi usually puts the verb at the end of the sentence.

English:

• The neighborhood is quiet

Hindi:

• Neighborhood quiet is
• मोहल्ला शांत है

This is one of the most important word-order differences between English and Hindi.

Because मोहल्ला is singular.

• है = is
• हैं = are

So:

• मोहल्ला शांत है। = The neighborhood is quiet.
• मोहल्ले शांत हैं। = The neighborhoods are quiet.

Also, हैं is used with honorific singular people, but that does not apply here.

Yes, मोहल्ला is a masculine singular noun.

That can matter for agreement in Hindi. For example, with a changing adjective:

• मोहल्ला बड़ा है। = The neighborhood is big.
• गली बड़ी है। = The lane/street is big.

Here, though, the adjective is शांत, and that adjective usually does not change form, so you do not see a masculine ending on it.

Because शांत is usually treated as an invariable adjective in modern Hindi.

That means it stays the same with different genders and numbers:

• मोहल्ला शांत है।
• गली शांत है।
• बच्चे शांत हैं।
• लड़कियाँ शांत हैं।

The adjective stays शांत; only the verb changes when needed.

It can mean all of these depending on context:

• quiet
• calm
• peaceful

With a place like मोहल्ला, it often suggests:

• the area is not noisy
• the atmosphere is calm
• the neighborhood feels peaceful

So it is a little broader than just literal silence.

The normal, neutral order is:

मोहल्ला शांत है।

Hindi can sometimes move words around for emphasis, for example:

शांत है मोहल्ला।

But that sounds marked, literary, or emphatic rather than basic everyday wording. As a learner, it is best to stick with:

मोहल्ला शांत है।

Add नहीं before है:

मोहल्ला शांत नहीं है।
= The neighborhood is not quiet.

A very common pattern in Hindi is:

subject + description + नहीं + है

The easiest way is to add क्या at the beginning:

क्या मोहल्ला शांत है?
= Is the neighborhood quiet?

In speech, intonation also helps. But for learners, using क्या is the simplest and clearest method.

You would make both the noun and the verb plural:

मोहल्ले शांत हैं।

Changes:

• मोहल्ला → मोहल्ले
• है → हैं

The adjective शांत stays the same.

Because Hindi spelling shows a doubled l sound there.

• ल्ल represents ll
• so मोहल्ला is pronounced something like mo-hal-laa

This kind of doubled consonant is very common in Hindi spelling, especially in words borrowed from Persian/Arabic or words that historically developed that way.