मैं हमेशा फोन बैग में रखती हूँ।

Because रखती हूँ is the form used by a female speaker.

In Hindi, the habitual form agrees with the speaker’s gender when the subject is मैं.

• मैं ... रखती हूँ = I keep/put ... (said by a woman)
• मैं ... रखता हूँ = I keep/put ... (said by a man)

So this sentence tells you that the speaker is female.

This is a very common Hindi pattern.

The sentence uses the present habitual:

• रखती = habitual participle of रखना (to keep / to place / to put)
• हूँ = am

Together:

• रखती हूँ = I habitually keep / I usually keep / I always keep

So Hindi often builds this kind of meaning with:

• main verb in habitual form
  • a form of होना

Examples:

• मैं पढ़ती हूँ = I study / I read
• मैं काम करती हूँ = I work / I do work

It can suggest either, depending on context.

रखना can mean:

• to put/place
• to keep

In this sentence, with हमेशा (always), it most naturally means something like:

• I always keep the phone in my bag or
• I always put my phone in my bag

English chooses between keep and put more sharply, but Hindi रखना can cover both ideas in everyday speech.

Yes, हमेशा can move around somewhat.

In this sentence:

• मैं हमेशा फोन बैग में रखती हूँ।

This is a natural word order: I always phone bag in keep.

You may also hear:

• मैं फोन हमेशा बैग में रखती हूँ।
• मैं फोन बैग में हमेशा रखती हूँ।

But the most neutral and common place for an adverb like हमेशा is before the object or before the part of the sentence it modifies.

Hindi word order is more flexible than English, but the main verb usually stays near the end.

Because Hindi uses postpositions, not prepositions.

In English:

• in the bag

In Hindi:

• बैग में
• literally: bag in

So में means in, but it comes after the noun.

Other common postpositions:

• पर = on
• से = from / with / by
• को = to / object marker
• के साथ = with

Because direct objects in Hindi often appear without को, especially when they are:

• inanimate
• general/non-specific in feel
• not being specially emphasized

So:

• मैं फोन बैग में रखती हूँ = natural

You might hear फोन को in some contexts, but here it would usually sound unnecessary or marked.

In everyday Hindi, को is much more common with:

• people
• animate beings
• specific objects being highlighted

For example:

• मैंने बच्चे को बुलाया। = I called the child.

Because this is not a perfective past sentence.

Hindi uses ने mainly with many transitive verbs in the perfective past.

Here the sentence is in the present habitual:

• मैं ... रखती हूँ not
• मैंने ... रखा

So no ने is needed.

Compare:

• मैं हमेशा फोन बैग में रखती हूँ। = I always keep the phone in my bag.
• मैंने फोन बैग में रखा। = I put the phone in the bag.

Yes, often you can.

Hindi frequently drops pronouns when the meaning is clear from context.

So:

• मैं हमेशा फोन बैग में रखती हूँ। and
• हमेशा फोन बैग में रखती हूँ।

can both work if it is already obvious who is speaking.

The verb ending हूँ already tells you the subject is I.

Still, including मैं is perfectly natural, especially if:

• you want emphasis
• you are contrasting yourself with someone else
• you are being especially clear

बैग is a borrowed word from English, but it is very common in Hindi.

Loanwords like this are assigned a grammatical gender in usage, often masculine, but in this sentence its gender does not really affect anything important.

Why not? Because:

• बैग is followed by में
• the verb is agreeing with मैं (the speaker), not with बैग

So even if you are unsure about the gender of बैग, this sentence stays the same:

• मैं हमेशा फोन बैग में रखती हूँ।

Because Hindi normally prefers Subject–Object–Verb order.

English:

• I always keep the phone in the bag.

Hindi:

• मैं हमेशा फोन बैग में रखती हूँ।
• literally closer to: I always phone bag in keep

This is one of the biggest differences English speakers notice. In Hindi, the main verb usually comes at the end or near the end.

Literally, it just says बैग में = in the bag.

Hindi often leaves possession unstated when it is obvious from context. So if someone says this in normal conversation, listeners will usually understand:

• I always keep my phone in my bag

If you want to say my bag explicitly, you could say:

• मैं हमेशा फोन अपने बैग में रखती हूँ।

That adds अपने = my own / my in this context.

Two things are especially important:

1. मैं

   • pronounced roughly like main in English, but with nasalization
   • the vowel is nasalized, so it is not exactly plain mai

2. हूँ

   • pronounced roughly hoon, also with nasalization
   • the nasalization matters in careful pronunciation

So the sentence sounds roughly like:

• main hamesha phone bag mein rakhti hoon but with nasalized vowels in मैं, में, and हूँ

Yes, absolutely.

In everyday Hindi, all of these are common depending on region and speaker:

• फोन
• मोबाइल
• मोबाइल फोन

So you could also say:

• मैं हमेशा मोबाइल बैग में रखती हूँ।

That would sound very natural too.