यह करतब मुश्किल है।

यह means this. It points to something near the speaker, or something currently being discussed.

So in यह करतब मुश्किल है, यह refers to this trick / this stunt / this feat.

A useful contrast:

• यह = this
• वह = that

In everyday speech, यह is often pronounced more like ये.

A natural pronunciation is roughly:

yeh kartab mushkil hai

A more detailed approximation:

• यह = yeh
• करतब = kar-tab
• मुश्किल = mush-kil
• है = hai

In fast speech, यह often sounds closer to yeh than to a careful yah.

करतब usually means something like:

• trick
• stunt
• feat
• sometimes skillful act

The exact English word depends on context.

For example:

• in a circus or performance context: stunt or trick
• in a skill/impressive-action context: feat

So the sentence could sound like:

• This stunt is difficult.
• This trick is difficult.
• This feat is difficult.

Hindi often puts things in this order:

this stunt difficult is

That is normal Hindi structure.

So:

• यह करतब = this stunt
• मुश्किल = difficult
• है = is

In English, we say This stunt is difficult.
In Hindi, the is word (है) usually comes at the end.

Because Hindi commonly places the verb at the end of the sentence.

Here, है is the present-tense form of to be for a singular subject:

• यह करतब मुश्किल है = This stunt is difficult

This is extremely common in Hindi:

• यह किताब अच्छी है। = This book is good.
• वह कमरा बड़ा है। = That room is big.

Because the subject is singular: यह करतब = this stunt.

Use:

• है with singular subjects
• हैं with plural subjects, or with respectful you

Compare:

• यह करतब मुश्किल है। = This stunt is difficult.
• ये करतब मुश्किल हैं। = These stunts are difficult.

Usually, मुश्किल does not change form here. It behaves like an indeclinable adjective in this kind of sentence.

So you can say:

• यह करतब मुश्किल है।
• यह किताब मुश्किल है।
• ये सवाल मुश्किल हैं।

The adjective मुश्किल stays the same; the verb changes if needed:

• singular: है
• plural: हैं

No. Hindi does not use articles like English a, an, and the in the same way.

So यह करतब naturally means this stunt without needing an extra word for the.

More generally:

• किताब can mean a book or the book, depending on context
• यह किताब means this book

Yes. कठिन also means difficult.

So both are possible:

• यह करतब मुश्किल है।
• यह करतब कठिन है।

A small nuance:

• मुश्किल is very common in everyday speech
• कठिन can sound a bit more formal or literary in some contexts

Both are correct.

This is a very common learner question.

In careful written Hindi:

• यह = this / he / she (near the speaker, depending on context)
• ये = these / sometimes they (near the speaker)

But in everyday spoken Hindi, people very often say ये where careful written Hindi would use यह.

So:

• formal/written: यह करतब मुश्किल है
• common spoken pronunciation: ये करतब मुश्किल है

That does not necessarily make it plural in speech. Context tells you whether it means this or these.

Yes. Even if the basic meaning is already clear, the exact nuance can shift a little.

करतब can refer to:

• a physical stunt
• a trick
• an impressive feat
• a skillful act

So the sentence might be understood as:

• This stunt is difficult
• This trick is difficult
• This feat is difficult

The surrounding context tells you which English word fits best.