أقرأ القصة في المكتبة قبل أن أعود إلى البيت.

Because أقرأ already tells you the subject is I. In the Arabic imperfect tense, the prefix أـ marks first-person singular.

So:

• أقرأ = I read / I am reading

You can still say أنا أقرأ if you want emphasis, contrast, or extra clarity, but in a normal sentence, Arabic often leaves the subject pronoun out.

أقرأ is in the imperfect tense. In Arabic, the imperfect can cover several ideas that English splits up:

• I read
• I am reading
• I will read (sometimes, depending on context)

In this sentence, the context قبل أن أعود إلى البيت helps show the timing. The exact English translation depends on context, but grammatically the verb form itself is the standard imperfect.

The verb قرأ means to read, and it normally takes a direct object in Arabic, just like in English.

So:

• أقرأ القصة = I read the story

You do not need a preposition like to or from before القصة. It is simply the thing being read.

الـ is the Arabic definite article, meaning the.

So:

• قصة = a story
• القصة = the story

The sentence uses القصة, so it is referring to a specific story, not just any story.

The preposition في means in or at, depending on context.

So:

• في المكتبة = in the library / at the library

This phrase tells you where the reading happens.
Also note:

• مكتبة = a library
• المكتبة = the library

So the phrase is definite: in the library.

قبل means before, but when Arabic follows it with a verb clause, it commonly uses أن.

So:

• قبل أن أعود = before I return

If you use a noun instead of a verb, then أن is not needed. For example:

• قبل العودة = before returning
• قبل رجوعي = before my return

So قبل أن is the normal pattern when before is followed by a verb.

After أن, a present/imperfect verb is normally put in the subjunctive.

So the fully vocalized form is:

• أعودَ

In normal unvocalized writing, you usually just see:

• أعود

So the spelling often looks the same, but grammatically the verb is in the subjunctive after أن.

This is a very common pattern in MSA:

• أن + imperfect verb

And in this sentence, قبل أن أعود means before I return.

The preposition إلى means to / toward, and it is commonly used with verbs of movement.

So:

• أعود إلى البيت = I return to the house/home

With عاد, standard MSA usually uses إلى to show the destination.

Also, Arabic often says البيت where English would simply say home. So even though English says go home or return home without the, Arabic naturally says:

• إلى البيت

If fully vocalized, the sentence is:

أقرأُ القصةَ في المكتبةِ قبلَ أن أعودَ إلى البيتِ.

Here is what is happening:

• أقرأُ: indicative imperfect, with ـُ
• القصةَ: direct object, so it is accusative
• في المكتبةِ: after a preposition, so المكتبةِ is genitive
• قبلَ: often treated here as an adverbial expression of time
• أعودَ: subjunctive after أن
• إلى البيتِ: after a preposition, so البيتِ is genitive

In everyday unvocalized Arabic, these short endings are usually not written, which is why learners often do not see them in normal text.

Yes, Arabic word order is somewhat flexible, but the original sentence is a very natural neutral order.

The given sentence starts with the verb:

• أقرأ القصة في المكتبة قبل أن أعود إلى البيت

That is a normal verbal sentence in Arabic.

You can change the order for emphasis, for example:

• في المكتبة أقرأ القصة قبل أن أعود إلى البيت
  This emphasizes in the library.

Or:

• أنا أقرأ القصة في المكتبة قبل أن أعود إلى البيت
  This emphasizes I.

But for a plain, unmarked statement, the original order is very good.

Yes, أقرأ can be tricky for English speakers.

A careful pronunciation is roughly:

• ʾaqraʾu

Important points:

• The first أ is a glottal stop plus a
• ق is a deep q sound, not an English k
• The final ء is another glottal stop

So you should not pronounce it like one smooth English word. There is a little stop at the end.

Similarly:

• أعود is roughly ʾaʿūdu

That word also has a sound English does not have very well, the letter ع.

It could do either, depending on context.

Because أقرأ is an imperfect verb, the sentence could describe:

• something happening now
• a usual habit
• a planned or expected action

For example, without extra context, Arabic often leaves this a bit open. The time phrase قبل أن أعود إلى البيت gives the sequence, but not necessarily whether it is a one-time event or a habit. Context tells you which meaning is intended.