पैंट नई है।

In Hindi, पैंट usually refers to one pair of pants as a single item of clothing, so it is often treated as singular.

That is why the sentence uses singular agreement:

• पैंट नई है। = one pair of pants is new

If you mean multiple pairs, Hindi would normally say:

• पैंटें नई हैं।

So English pants and Hindi पैंट do not behave exactly the same grammatically.

In standard Hindi, पैंट is normally feminine.

You can see that from the adjective:

• नई = feminine form of new

So:

• पैंट नई है। is correct
• पैंट नया है। would sound wrong in standard Hindi

As with many Hindi nouns, especially loanwords, the gender is something you usually just have to learn.

Because नई agrees with the noun पैंट, and पैंट is feminine.

The adjective नया changes like this:

• नया = masculine singular
• नई = feminine singular
• नए = masculine plural

So:

• नया लड़का = new boy
• नई किताब = new book
• पैंट नई है। = the pants are new / the pair of pants is new

Because पैंट is being treated as singular here.

In the present tense, है and हैं mainly show number:

• है = is
• हैं = are

So:

• पैंट नई है। = one pair is new
• पैंटें नई हैं। = multiple pairs are new

Also, है does not change for masculine vs. feminine here. Gender is shown by नई, not by है.

Both patterns exist, but they mean slightly different things.

In पैंट नई है, नई is part of the predicate:

• literally: The pants are new

Here the structure is:

• noun + adjective + है

But when the adjective directly modifies the noun, it usually comes before:

• नई पैंट = new pants / a new pair of pants

So compare:

• नई पैंट = new pants
• पैंट नई है। = the pants are new

You would usually say:

• पैंटें नई हैं।

Changes:

• पैंट → पैंटें for plural
• है → हैं for plural

Notice that नई stays the same, because the feminine form नई is used for both singular and plural in this kind of sentence.

Hindi does not normally use articles the way English does.

So पैंट नई है। can mean, depending on context:

• The pants are new
• A pair of pants is new
• This pair of pants is new

Context tells you which meaning is intended. If needed, Hindi can be more specific:

• यह पैंट नई है। = these pants / this pair of pants is new
• मेरी पैंट नई है। = my pants are new

Yes. पैंट is a borrowed word from English pant/pants.

It is very common in everyday Hindi. You may also hear other clothing words, but पैंट is completely normal and natural.

Like many loanwords in Hindi, it has been assigned a grammatical gender—here, feminine.

It is pronounced approximately like English pant, but with a Hindi-style ट, which is a retroflex t sound.

A simple learner-friendly approximation is:

• paiṇṭ / pæṇṭ / peṇṭ depending on accent and teaching style

The important points are:

• it is one syllable
• the ending ट is a firm Hindi t sound
• it is a loanword, so pronunciation may vary a little across speakers

In a full standard sentence, you should say पैंट नई है।

Leaving out है may happen in:

• very casual speech
• notes, labels, or headlines

But for normal learning and correct standard Hindi, include है:

• पैंट नई है।

That is the complete and safest form to use.