Because इस is the oblique form of यह.
In Hindi, when a noun phrase is followed by a postposition such as का, को, में, से, etc., words like यह / वह usually change to their oblique forms:
So:
Here, the phrase इस काम is followed by का, so यह becomes इस.
Because का / की / ke agrees with the noun that comes after it here, namely मकसद.
मकसद is treated as masculine singular, so the correct form is का:
Compare:
So in this sentence, का matches मकसद.
In Hindi, question words often stay in the place where the answer would normally go.
Statement:
Question:
So क्या appears where the missing information goes.
This is different from sentence-initial क्या, which is often used for yes/no questions:
But here क्या means what, so it stays in the slot of the thing being asked about.
मकसद means purpose, aim, objective, or sometimes motive, depending on context.
In this sentence, it most naturally means:
It is a very common everyday word. A slightly more formal/Sanskrit-based alternative is उद्देश्य:
That means almost the same thing, but उद्देश्य sounds a bit more formal or official.
It can mean any of those, depending on context.
काम is a broad word. It may refer to:
So इस काम का मकसद क्या है? could be understood as:
The exact English choice depends on the situation.
There isn’t one, because Hindi does not usually use articles like English a/an/the.
So Hindi often leaves that idea to context.
Depending on context, this could correspond to:
Hindi speakers do not need separate words for a and the in most cases.
Yes, in standard Hindi this sentence normally takes है.
है is the present-tense form of to be here:
If you remove है, it may sound incomplete in standard written Hindi. In very casual speech, people sometimes drop forms of to be, but learners should keep है here.
A very literal breakdown is:
So, very literally:
But natural English is:
Hindi often puts the possessor/related noun first and then uses का/की/के to link it to the main noun.
You would use उस instead of इस:
This follows the same pattern:
So:
A common transliteration is:
is kaam ka maksad kya hai?
Rough pronunciation:
So the whole sentence sounds roughly like:
is kaam kaa mak-sad kyaa hai?
The aa in काम and का is longer than the vowel in English cup or cat.