यह खिड़की छोटी है।

A word-by-word breakdown is:

• यह = this
• खिड़की = window
• छोटी = small (feminine singular form)
• है = is

So the sentence structure is literally:

• This window small is

Natural English: This window is small.

Because खिड़की is a feminine noun in Hindi.

In Hindi, adjectives often agree with the noun’s gender and number.

For the adjective छोटा (small):

• छोटा = masculine singular
• छोटी = feminine singular
• छोटे = masculine plural or masculine oblique in some contexts

Since खिड़की is feminine singular, the correct form is छोटी.

In Hindi, grammatical gender is something you usually have to learn with the noun. There is not always a perfect rule.

So it is best to learn nouns like this:

• खिड़की — feminine
• घर — masculine
• किताब — feminine

A good habit is to memorize each noun together with an adjective:

• छोटी खिड़की = small window
• बड़ा घर = big house

That helps you remember the noun’s gender naturally.

है is the present tense form of to be, meaning is.

In this sentence, it completes the statement:

• यह खिड़की छोटी है। = This window is small.

In normal standard Hindi, you usually need है in simple sentences like this.

Compare:

• यह खिड़की छोटी है। = This window is small.
• यह खिड़की छोटी। = incomplete or unnatural in standard Hindi

So yes, in this kind of sentence, है is normally required.

Hindi and English often use different default word order.

English:

• This window is small.

Hindi:

• यह खिड़की छोटी है।
• literally: This window small is.

Hindi usually puts the main descriptive word before the form of to be. So adjective + है is very common:

• कमरा बड़ा है। = The room is big.
• किताब नई है। = The book is new.

This word order is completely normal in Hindi.

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

So खिड़की can mean:

• a window
• the window
• just window

The context tells you which one is meant.

In this sentence, यह already makes it definite, so यह खिड़की naturally means this window.

In careful spelling, it is यह, but in everyday speech it is very often pronounced more like yeh.

So learners commonly hear:

• यह written
• yeh spoken

This is normal.

Also, in modern spoken Hindi:

• यह often sounds like yeh = this
• वह often sounds like voh = that

So do not be surprised if the pronunciation you hear sounds slightly different from the spelling.

This is a very common source of confusion.

In standard written Hindi:

• यह = this (singular)
• ये = these (plural)

Examples:

• यह खिड़की छोटी है। = This window is small.
• ये खिड़कियाँ छोटी हैं। = These windows are small.

But in everyday spoken Hindi, people often use ये to mean this as well. So you may hear:

• ये खिड़की छोटी है।

Even though standard textbook Hindi would usually prefer:

• यह खिड़की छोटी है।

So:

• यह is the standard singular written form
• ये is often used informally in speech for singular too

If the noun were masculine singular, the adjective would usually change to the masculine form.

For example:

• यह कमरा छोटा है। = This room is small.

Compare:

• यह खिड़की छोटी है। = This window is small.
• यह कमरा छोटा है। = This room is small.

So the adjective changes to match the noun:

• feminine noun → छोटी
• masculine noun → छोटा

You would say:

• ये खिड़कियाँ छोटी हैं।

Here is what changed:

• यह → ये = this → these
• खिड़की → खिड़कियाँ = window → windows
• छोटी stays feminine plural-looking in this kind of predicate use
• है → हैं = is → are

So:

• यह खिड़की छोटी है। = This window is small.
• ये खिड़कियाँ छोटी हैं। = These windows are small.

A simple learner-friendly pronunciation is:

• यह = yeh
• खिड़की = khi-rkee or khid-kee
• छोटी = cho-tee
• है = hai

A rough full pronunciation:

• yeh khidkee chhoṭee hai

A few helpful notes:

• ख is an aspirated k sound, like a strong k with a puff of air
• ड़ in खिड़की is a flapped sound, somewhat like a soft tapped r/d
• छ is like an aspirated ch
• ै in है sounds roughly like ai in air, though not exactly the same

You do not need perfect pronunciation immediately; being understood matters most first.