Okolí domu je klidné.

Because okolí is a singular neuter noun in Czech. It refers to the surrounding area as one whole thing.

So in Czech:

• okolí domu je klidné = literally something like the area around the house is მშვიდ/quiet

Even though English often uses the plural surroundings, Czech normally uses singular okolí.

Okolí means the surrounding area, the vicinity, or the neighborhood around something.

In this sentence, okolí domu means:

• the area around the house
• the immediate surroundings of the house

It does not mean the house itself. It refers to what is around it.

Because okolí is followed by the genitive case to show surroundings of what.

• dům = nominative singular, house
• domu = genitive singular, of the house

So:

• okolí domu = the surroundings of the house

This is a very common Czech pattern:

• střecha domu = the roof of the house
• centrum města = the center of the city
• okolí školy = the surroundings of the school

Because klidné agrees with okolí, which is neuter singular.

In Czech, adjectives must agree with the noun they describe in:

• gender
• number
• case

Here, klidné is a predicate adjective used with je, but it still agrees with the subject:

• masculine singular: dům je klidný
• feminine singular: ulice je klidná
• neuter singular: okolí je klidné

So klidné is the correct neuter singular form.

Je is the 3rd person singular form of být = to be.

Since the subject okolí is singular, Czech uses singular je:

• okolí je klidné = the surroundings/area is quiet

This works just like English is.

In normal standard Czech, no. In the present tense, Czech usually keeps je in this kind of sentence.

So:

• Okolí domu je klidné. = correct

Leaving out je would sound incomplete in standard Czech.

Okolí domu je klidné. is the normal, neutral word order.

It follows a simple pattern:

• subject: okolí domu
• verb: je
• complement: klidné

You can change the order for emphasis, but the neutral version is the one you see here.

For example:

• Klidné je okolí domu. = more marked, emphasizing quiet
• Okolí je klidné. = if domu is already understood from context

They are related, but they are not the same structure.

• okolí domu = the surroundings of the house
  This is a noun phrase.
• kolem domu = around the house
  This is a prepositional phrase.

Compare:

• Okolí domu je klidné. = The surroundings of the house are quiet.
• Kolem domu je klid. = Around the house, there is peace/quiet.

So okolí domu names the area itself, while kolem domu describes location.

Because Czech has no articles like English a and the.

So dům / domu can mean:

• a house
• the house

The exact meaning depends on context.

That means okolí domu could be understood as:

• the surroundings of the house
• the surroundings of a house

In real use, context tells you which one is meant.

A simple pronunciation guide is:

OH-koh-lee DOH-moo yeh KLEED-neh

A few useful points:

• Czech stress is usually on the first syllable of each word:
  • Okolí
  • DOmu
  • JE
  • KLIdné
• í in okolí is a long vowel
• é in klidné is also a long vowel
• j in je sounds like English y in yes

So je is pronounced like yeh, not like English jee.

It can mean several closely related things, depending on context:

• quiet
• calm
• peaceful

So Okolí domu je klidné might suggest:

• there is not much noise there
• the area feels calm
• the neighborhood is peaceful

The exact English translation depends on the situation, but the Czech sentence itself is natural and broad enough to cover all of these shades of meaning.