بعد العمل أذهب إلى الصيدلية لأنني أحتاج إلى دواء.

بعد العمل means after work.

Grammatically:

• بعد = after
• العمل = the work / work

Together they form a time expression. Arabic often starts a sentence with a time phrase like this, just as English can say After work, I go...

If fully vowelled, it is:

• بَعْدَ الْعَمَلِ

Here:

• بعدَ is a time adverb
• العملِ is in the genitive because it comes after بعد in an iḍāfa-type structure

Because the verb itself already tells you the subject.

• أذهب = I go
• أحتاج = I need

The prefix أ- on a present-tense verb marks first person singular.

So Arabic usually does not need a separate أنا here. You could say أنا أذهب or أنا أحتاج, but that would add emphasis, not basic meaning.

In Arabic, the present tense (المضارع) can express:

• a present action
• a habitual action
• sometimes a near-future action, depending on context

So بعد العمل أذهب إلى الصيدلية most naturally means something like:

• After work, I go to the pharmacy
• or After work, I’m going to the pharmacy

The exact English translation depends on context, but the Arabic present tense is normal here.

Because both verbs need it in this sentence:

• أذهب إلى = to go to
• أحتاج إلى = to need

So:

• أذهب إلى الصيدلية = I go to the pharmacy
• أحتاج إلى دواء = I need medicine

This is very common in Arabic: a verb may regularly take a certain preposition, and it does not always match English perfectly. So it is best to learn verb + preposition together.

الصيدلية means the pharmacy.

The ending ـة is called tāʾ marbūṭa, and it often marks a feminine noun.

So:

• صيدلية = pharmacy
• الصيدلية = the pharmacy

Because it is feminine, any adjective describing it would also be feminine:

• الصيدلية الكبيرة = the big pharmacy

لأن means because, but here the sentence needs because I...

So Arabic uses:

• لأنني = because I...
• A common alternative spelling/form is لأني

This is the normal way to introduce a clause like:

• لأنني أحتاج إلى دواء = because I need medicine

In other words:

• لأن introduces the reason
• ـني gives the I part

This is a very good grammar question.

The short answer is that لأن behaves like a particle that normally takes its own subject. So in لأنني:

• لأن = because
• ني = a pronoun meaning I

Then أحتاج إلى دواء is the rest of the clause.

So even though أحتاج already shows I, Arabic still commonly uses لأنني as the standard way to say because I...

This is one of those patterns that is best learned as a whole chunk:

• لأنني أريد... = because I want...
• لأنني أعرف... = because I know...
• لأنني أحتاج... = because I need...

Because the sentence means medicine in a general sense, not the specific medicine.

So:

• دواء = medicine / a medicine
• الدواء = the medicine

Here the speaker just needs some medicine, not one already identified. That is why the indefinite form is natural.

If fully vowelled after إلى, it would be:

• دَوَاءٍ

because it is genitive after the preposition إلى.

The sentence is organized like this:

• بعد العمل = time expression
• أذهب = verb
• إلى الصيدلية = destination
• لأنني أحتاج إلى دواء = reason

So the full structure is:

time + action + place + reason

Arabic word order is flexible, and starting with a time phrase is very natural. English can do the same:

• After work, I go to the pharmacy because I need medicine.

It would be:

بَعْدَ الْعَمَلِ أَذْهَبُ إِلَى الصَّيْدَلِيَّةِ لِأَنَّنِي أَحْتَاجُ إِلَى دَوَاءٍ.

Some useful notes:

• بعدَ: final fatḥa
• العملِ: kasra because it follows بعد in this structure
• أذهبُ: final ḍamma in the normal indicative present
• الصيدليةِ: kasra after إلى
• دواءٍ: kasra after إلى and indefinite

In normal everyday writing, these short vowels are usually omitted.

Yes. This is a natural and correct MSA sentence.

It sounds clear, standard, and appropriate for written Arabic or careful spoken Arabic. A colloquial dialect might use different words or phrasing, but for Modern Standard Arabic this sentence is completely normal.