من باید آن را امشب بخوانم، اما خواهرم میخواهد آن را فردا بخواند.

را marks the definite direct object of the verb.

So in آن را بخوانم, the thing being read is آن, and را shows that آن is the object.

A very literal breakdown is:

• آن = that / it
• را = object marker
• بخوانم = I read / I should read

In natural English, you usually do not translate را as a separate word. It is just a grammar marker.

In spoken Persian, را is often pronounced more like رو.

باید expresses necessity: must, have to, or sometimes should, depending on context.

In this sentence, it shows that the speaker has an obligation to do something.

A useful point: باید itself does not change for person.

You say:

• من باید...
• تو باید...
• او باید...

The person is shown by the verb that follows, not by changing باید.

After باید, Persian normally uses the present subjunctive form of the verb, not the infinitive.

So:

• خواندن = to read
• بخوانم = that I read / I read (subjunctive form, used after باید)

This is very common in Persian:

• باید بروم = I must go
• باید بخوانم = I must read

For an English speaker, this may feel unusual, because English often uses must + base verb, while Persian uses باید + subjunctive verb.

The ending changes to match the subject.

• بخوانم = I read / I should read
• بخواند = he/she reads / he/she should read

In your sentence:

• من goes with بخوانم
• خواهرم goes with بخواند

So the verb ending tells you who is doing the action.

Very roughly:

• -م = I
• -د = he/she/it

That بـ is part of the subjunctive form.

With many verbs, the present subjunctive is made with:

• بـ
  • present stem + personal ending

Here the verb is خواندن and its present stem is خوان.

So:

• ب + خوان + م → بخوانم
• ب + خوان + د → بخواند

This بـ often appears after words like:

• باید
• می‌خواهد
• لازم است
• expressions of desire, necessity, possibility, etc.

The dictionary form is خواندن, meaning to read.

Like many Persian verbs, it has:

• past stem: خواند
• present stem: خوان

The form in your sentence is built from the present stem:

• خوان
• بخوانم
• بخواند

This stem system is very important in Persian verb conjugation.

Yes, Persian often drops subject pronouns because the verb ending already tells you the person.

So باید آن را امشب بخوانم already means I must read it tonight, even without من.

Here, من is probably included for clarity or contrast, especially because the sentence compares two people:

• I must read it tonight,
• but my sister wants to read it tomorrow.

So من helps set up that contrast.

خواهرم means my sister.

It is made of:

• خواهر = sister
• -م = my

This -م is a possessive ending attached directly to the noun.

So:

• خواهرم = my sister
• کتابم = my book
• دوستم = my friend

Persian often expresses possession this way instead of using a separate word like English my.

You can also say خواهرِ من, but خواهرم is very common and natural.

This is the verb می‌خواهد, meaning wants.

The standard spelling is:

• می‌خواهد

with a half-space after می.

You may also see:

• میخواهد

especially in informal typing or when people do not use the half-space correctly.

Grammatically, it is:

• می = present/imperfective marker
• خواه = present stem of خواستن
• د = third-person singular ending

So می‌خواهد = he/she wants

In your sentence, it agrees with خواهرم, which is third-person singular.

Because خواستن in the sense of to want to do something is commonly followed by a subjunctive verb.

So:

• می‌خواهد بخواند = she wants to read

This pattern is very common:

• می‌خواهم بروم = I want to go
• می‌خواهند ببینند = they want to see
• می‌خواهد بخواند = she wants to read

Again, English uses want + infinitive, but Persian usually uses خواستن + subjunctive.

Yes, Persian can sometimes omit it if the object is already clear from context.

So a shorter version could be:

• من باید آن را امشب بخوانم، اما خواهرم می‌خواهد فردا بخواند.

That would still be understandable.

But repeating آن را is perfectly normal and can make the sentence clearer, especially for contrast or emphasis. Persian often repeats things that English might omit.

آن literally means that, but depending on context it can also function like it, especially for non-human things already known from context.

So in this sentence, آن را can naturally be understood as it.

A useful distinction:

• او = he / she
• آن = that / it

In everyday spoken Persian, people often use اون instead of آن.

So in conversation, you might hear:

• اونو امشب بخونم...

instead of the more formal/written-style آن را امشب بخوانم.

Not completely. Persian word order is fairly flexible, though the neutral pattern is usually subject + object + time/place + verb.

In your sentence:

• من = subject
• آن را = object
• امشب = time
• بخوانم = verb

That order is very natural.

You can sometimes move time expressions like امشب and فردا for emphasis, for example:

• من باید امشب آن را بخوانم
• خواهرم می‌خواهد فردا آن را بخواند

These are also natural.

The main thing is that the verb usually comes near the end of the clause.

No. اما is correct and fairly standard, especially in writing.

Another very common word is ولی.

So this sentence could also be said as:

• من باید آن را امشب بخوانم، ولی خواهرم می‌خواهد آن را فردا بخواند.

Both are natural. Very roughly:

• اما can feel a bit more formal or written
• ولی is extremely common in everyday speech

A colloquial version might be something like:

• من باید اونو امشب بخونم، اما/ولی خواهرم می‌خواد اونو فردا بخونه.

Some common spoken changes are:

• آن را → اونو
• بخوانم → بخونم
• می‌خواهد → می‌خواد
• بخواند → بخونه

The written sentence you gave is perfectly good Persian, but some parts of it sound more formal or written than casual everyday speech.