यह फ्लैट खाली है।

A natural pronunciation is:

yah flaiṭ khālī hai

A few notes:

• यह is often pronounced more like yah in everyday speech.
• फ्लैट is a borrowed word from English flat, adapted to Hindi pronunciation.
• खाली sounds like khaa-lee.
• है sounds like hai, roughly like heh or hai depending on accent.

So the whole sentence sounds approximately like:

yah flaiṭ khaa-lee hai

यह means this and refers to something near the speaker.

So:

• यह फ्लैट = this flat
• वह फ्लैट = that flat

Hindi often distinguishes:

• यह = this
• वह = that

In actual speech, learners will also hear:

• ये used for this/these
• वो used for that/those

But in careful written Hindi, यह is the standard form here.

Yes, this is completely normal. फ्लैट is an English loanword used widely in Hindi, especially in cities.

Hindi often borrows English words and writes them in Devanagari:

• फ्लैट = flat
• बस = bus
• ट्रेन = train
• ऑफिस = office

So this sentence is grammatically Hindi, even though one word comes from English.

खाली usually means empty, vacant, or unoccupied, depending on context.

With फ्लैट, it commonly means:

• empty
• vacant
• not occupied

So the sentence could mean:

• This flat is empty.
• This flat is vacant.
• This apartment is unoccupied.

The exact English translation depends on context.

Hindi normally puts the verb at the end, unlike English.

So Hindi follows a pattern like:

यह फ्लैट खाली है
literally: This flat empty is

That is normal Hindi word order.

English:

• This flat is empty

Hindi:

• This flat empty is

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

है is the present tense form of to be for a singular subject in sentences like this.

Here it means is:

• यह फ्लैट खाली है = This flat is empty

Some useful comparisons:

• मैं खुश हूँ = I am happy
• वह यहाँ है = He/She is here
• यह अच्छा है = This is good

So in your sentence, है links फ्लैट with खाली, just like is in English.

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

So:

• यह फ्लैट can mean this flat
• no separate article is needed

Because यह already means this, the meaning is clear without an article.

More generally:

• कमरा बड़ा है = The room is big / A room is big depending on context
• Hindi relies much more on context than English for this.

In this sentence, खाली does not change. It is an invariable adjective here.

Many Hindi adjectives do change, especially those ending in -ा:

• अच्छा लड़का
• अच्छी लड़की
• अच्छे लड़के

But खाली usually stays the same:

• खाली फ्लैट
• खाली जगह
• खाली कमरे
• खाली कुर्सियाँ

So whether the noun is masculine, feminine, singular, or plural, खाली typically remains खाली.

It is often treated as masculine in Hindi, though with some loanwords actual usage can vary by speaker.

In many everyday contexts, people would use masculine agreement with फ्लैट, for example:

• यह फ्लैट बड़ा है = This flat is big

Here बड़ा is masculine singular.

In your sentence, though, you cannot tell from खाली, because खाली does not change by gender.

In everyday spoken Hindi, yes, many people say ये where formal written Hindi would use यह.

So you may hear:

• यह फ्लैट खाली है in careful or formal Hindi
• ये फ्लैट खाली है in casual speech

This can confuse learners, because ये can also mean these in formal grammar. But in everyday speech, ये very often means this as well.

So:

• यह = standard written form
• ये = very common spoken form

In standard Hindi, you should keep है in a full sentence like this:

यह फ्लैट खाली है।

In very casual speech, people may sometimes drop it if the meaning is obvious, especially in short conversational fragments:

• फ्लैट खाली?
• यह फ्लैट खाली?

But for correct, complete Hindi, especially as a learner, use है.

Usually it describes a current state: the flat is empty or vacant right now.

That is because खाली often refers to condition or status:

• a seat can be खाली
• a room can be खाली
• a schedule slot can be खाली

So for a flat, it usually means:

• no one is living there at the moment
• or there is nothing in it
• or it is available

The exact nuance depends on context.