मेरा भाई रोज़ रात को अंग्रेज़ी लिखता है।

Because भाई is a masculine singular noun, and मेरा agrees with it.

• मेरा = my (used with masculine singular nouns)
• मेरी = my (used with feminine singular nouns)
• मेरे = my (used with masculine plural nouns, and in some oblique contexts)

So:

• मेरा भाई = my brother
• मेरी बहन = my sister

Even though the speaker could be male or female, मेरा is chosen based on भाई, not on the speaker.

The -ता form is part of the habitual present in Hindi. It shows that the action happens regularly or habitually.

In this sentence:

• लिखता है = writes / does write / writes regularly

Because the subject is भाई (masculine singular), the verb takes the masculine singular habitual form:

• लिखता है = he writes
• लिखती है = she writes

So मेरा भाई ... लिखता है means my brother writes ... as a regular action.

In Hindi, the habitual form usually works with a form of होना (to be).

So:

• लिखता by itself is not usually a complete everyday sentence here
• लिखता है is the normal full form

This structure is very common:

• वह पढ़ता है = he studies / he reads
• वह खेलती है = she plays
• मैं जाता हूँ = I go

So in मेरा भाई रोज़ रात ko अंग्रेज़ी लिखता है, the है helps complete the present habitual expression.

रोज़ means every day or daily.

In Hindi, time expressions like रोज़ are often placed before the rest of the action, but word order can be somewhat flexible.

Here:

• मेरा भाई रोज़ रात को अंग्रेज़ी लिखता है। = My brother writes English every night / every day at night.

You may also hear similar placements in other sentences, such as:

• वह रोज़ स्कूल जाता है। = He goes to school every day.
• मैं रोज़ हिंदी पढ़ता हूँ। = I study Hindi every day.

So रोज़ is an adverb of frequency.

Here को is being used with a time expression: रात को = at night / in the night.

This is a very common Hindi pattern:

• सुबह को = in the morning
• शाम को = in the evening
• रात को = at night

In everyday Hindi, people also very often say simply:

• रात में = at night
• सुबह = in the morning
• शाम को = in the evening

So रात को is a natural time phrase telling us when he writes.

No. Here अंग्रेज़ी is the direct object of लिखता है.

• अंग्रेज़ी लिखता है = writes English

Many direct objects in Hindi appear without a postposition.

को is often used with:

1. specific people or animate objects
2. sometimes definite/specific objects
3. indirect objects

But with language names used as the thing being written, spoken, learned, etc., Hindi usually just uses the noun directly:

• वह हिंदी बोलता है। = He speaks Hindi.
• मैं अंग्रेज़ी सीखता हूँ। = I learn English.
• वह उर्दू लिखती है। = She writes Urdu.

So अंग्रेज़ी here is simply the object: the thing he writes.

In normal usage, अंग्रेज़ी लिखता है usually means writes in English.

Hindi often uses language names this way:

• हिंदी बोलना = to speak Hindi
• अंग्रेज़ी पढ़ना = to study/read English
• उर्दू लिखना = to write in Urdu

So the sentence most naturally means that the brother does his writing using the English language, not that he is literally writing the word English over and over.

The basic Hindi word order is usually Subject – Object/Adverbials – Verb.

In this sentence:

• मेरा भाई = subject
• रोज़ = frequency adverb
• रात को = time expression
• अंग्रेज़ी = object
• लिखता है = verb

So the structure is roughly:

My brother + every day + at night + English + writes

This is normal for Hindi, where the verb usually comes at the end.

Yes, very naturally.

Because the sentence contains both:

• रोज़ = every day
• रात को = at night

the smooth English translation is often:

• My brother writes English every night.

That sounds more natural in English than a very literal version like:

• My brother writes English every day at night.

So both capture the meaning, but every night is usually the best natural translation.

You would need to change both the possessive and the verb to match a feminine subject:

• मेरी बहन रोज़ रात को अंग्रेज़ी लिखती है।

Changes:

• मेरा भाई → मेरी बहन
• लिखता है → लिखती है

That is because बहन is feminine, so the adjective and habitual verb form both change accordingly.

They can move around somewhat, because Hindi word order is flexible as long as the verb stays near the end and the sentence remains clear.

For example, these can all be natural depending on emphasis:

• मेरा भाई रोज़ रात को अंग्रेज़ी लिखता है।
• मेरा भाई रात को रोज़ अंग्रेज़ी लिखता है।
• रोज़ मेरा भाई रात को अंग्रेज़ी लिखता है।

But the given version is very normal and neutral.

Hindi often uses word order to change emphasis rather than basic meaning.