उसका फोन मेरे पास है।

उसका means his, her, or sometimes its.

Hindi does not mark natural gender in this possessive form the way English does, so उसका फोन can mean:

• his phone
• her phone

You usually understand which one from context.

Because Hindi possessives agree with the thing being possessed, not with the owner.

Here, the possessed noun is फोन, which is treated as masculine singular in Hindi. So the correct form is:

• उसका फोन = his/her phone

Compare:

• उसकी किताब = his/her book
  because किताब is feminine
• उसके जूते = his/her shoes
  because जूते is masculine plural

So उसका is chosen because फोन is masculine singular.

Because पास is used like a postposition here, and pronouns change form before postpositions.

The pronoun मैं becomes मेरे before a postposition:

• मैं = I
• मेरे = me/my in the oblique form used before postpositions

So:

• मेरे पास = with me / near me / in my possession

You cannot say मैं पास here.

Also, मेरा is a possessive adjective meaning my, so मेरा पास is not correct.

Literally, मेरे पास means near me or by me.

But in very common Hindi usage, it often means:

• with me
• in my possession
• I have

So उसका फोन मेरे पास है literally feels like:

• His/her phone is with me

This is the normal Hindi way to express possession in many cases.

Hindi usually does not use a direct equivalent of English have in this kind of sentence.

Instead of saying:

• I have his phone

Hindi typically says something like:

• His phone is with me
• मेरे पास उसका फोन है

A very common pattern is:

• X के पास Y है = X has Y

Examples:

• मेरे पास पैसा है। = I have money.
• उसके पास कार है। = He/She has a car.

So this sentence follows a very normal Hindi possession pattern.

Because the verb agrees with the thing being talked about as existing/being located, which here is फोन.

• फोन is masculine singular
• so the verb is है

It is not agreeing with मैं in मेरे पास.

That is why:

• उसका phone मेरे पास है। = singular thing
• उसके फोन मेरे पास हैं। = plural things

So हूँ would be wrong here.

Yes, फोन is normally treated as masculine.

That is why you get:

• उसका फोन
• मेरा फोन
• फोन है

If you made it plural, you would usually say:

• फोन हैं
• उसके फोन

Many borrowed nouns in Hindi still get assigned a grammatical gender, and फोन is commonly masculine.

Yes. Hindi word order is flexible, though some versions sound more natural in certain contexts.

These are both natural:

• उसका फोन मेरे पास है।
• मेरे पास उसका फोन है।

The difference is mostly about emphasis:

• उसका फोन मेरे पास है puts a little more focus on his/her phone
• मेरे पास उसका फोन है puts a little more focus on with me / I have it

Both are correct.

Usually it suggests current possession or the phone is with me right now.

So it often means something like:

• I’m holding his/her phone
• I have his/her phone with me
• His/her phone is currently in my possession

It does not necessarily mean you own it.

In fact, because the sentence says his/her phone, the natural interpretation is that it belongs to someone else and is currently with you.

Yes.

Since उसका comes from वह, it can often be understood as:

• his
• her
• that person’s
• that one’s

So depending on context, उसका फोन could mean:

• his phone
• her phone
• that person’s phone

Hindi often leaves this to context more than English does.

Usually मेरे पास is the natural choice here.

• मेरे पास है = I have it / it is with me
• मेरे साथ है = it is together with me / accompanying me

मेरे साथ is used more for people or things accompanying someone:

• वह मेरे साथ है। = He/She is with me.
• बैग मेरे साथ है। = The bag is with me / accompanying me

For possession like I have his phone, मेरे पास is much more standard and natural.

Not necessarily.

You would still say:

• उसका फोन मेरे पास है।

That is because उसका agrees with फोन, not with the gender of the owner.

So whether the owner is male or female, if the possessed noun is फोन (masculine singular), the form stays उसका.

That is often surprising for English speakers, because English possessives reflect the owner:

• his phone
• her phone

But Hindi here reflects the noun possessed, not the possessor.