من آن دارو را از دکتری که دیروز دیدم خریدم.

را marks the direct object of the verb. Here, it shows that آن دارو is the thing that was bought.

A few useful points:

• It usually does not get translated as a separate English word.
• It is most often used with a specific or definite object.
• In speech, را is often pronounced رو.

So آن دارو را means something like that medicine as the specific thing being acted on.

Because Persian normally follows a subject–object–verb pattern, unlike English, which is usually subject–verb–object.

So the structure here is roughly:

• من = I
• آن دارو را = that medicine
• از دکتری که دیروز دیدم = from the doctor / a doctor that I saw yesterday
• خریدم = bought

The relative clause also follows the same tendency, so دیدم comes at the end of که دیروز دیدم.

Here که introduces a relative clause. In English, that is the part with words like who, whom, that, or which.

So:

• دکتری که دیروز دیدم = the/a doctor that I saw yesterday

In Persian, که does not change form the way English does. The same که can cover meanings like:

• who
• whom
• that
• which

You understand the exact English equivalent from context.

This is a very common learner question. The -ی on دکتری can be tricky because it does not always map neatly to English.

In many cases, -ی can mark something like a/an:

• دکتری = a doctor

But before a relative clause with که, Persian often uses this form very naturally, and it does not always force an indefinite meaning in English.

So دکتری که دیروز دیدم can be a normal Persian structure for a noun being defined by the clause که دیروز دیدم. Depending on context, English may translate it as:

• a doctor that I saw yesterday
• or the doctor that I saw yesterday

So the important thing is: do not assume that the final -ی always has to be translated as a separate English article.

Persian relative clauses often leave that role understood rather than stating it explicitly.

In English:

• the doctor whom I saw yesterday
• the doctor that I saw yesterday

In Persian:

• دکتری که دیروز دیدم

The doctor is understood as the object of دیدم.

Also, Persian often does not need an extra pronoun there. In more colloquial speech, some speakers might say:

• دکتری که دیروز دیدمش

where -ش means him/her. But your sentence without it is completely normal and standard.

از usually means from.

Here it marks the source or seller:

• از دکتری... خریدم = I bought [it] from a doctor / the doctor...

So it tells you where the medicine came from.

Because demonstratives like این and آن go directly before the noun in Persian.

So you say:

• این کتاب = this book
• آن دارو = that medicine

There is no ezafe between the demonstrative and the noun.

Ezafe appears after the noun when the noun is followed by another modifier, for example:

• آن داروی خوب = that good medicine

So in your sentence, آن دارو is exactly what you would expect.

Yes. Persian often drops subject pronouns when the verb already makes the subject clear.

Since خریدم already means I bought, the sentence could simply be:

• آن دارو را از دکتری که دیروز دیدم خریدم.

Adding من is still correct, but it may add a little emphasis, contrast, or clarity.

Persian does not have a separate word exactly like English the.

Instead, definiteness and specificity are often shown by things like:

• context
• را
• demonstratives such as این and آن
• relative clauses

In this sentence:

• آن دارو is clearly specific because of آن
• دکتری که دیروز دیدم is identified by the relative clause

For indefiniteness, Persian can use:

• یک
• or the suffix -ی

But Persian does not match English article usage one-for-one, so it is better to think in terms of specificity and context, not just a/the.

Yes. Both are simple past, first person singular.

• دیدم = I saw
• خریدم = I bought

The -م ending shows I in both verbs.

So the sentence contains:

• a main past-tense verb: خریدم
• a past-tense verb inside the relative clause: دیدم

A very natural colloquial version would be:

• من اون دارو رو از دکتری که دیروز دیدم خریدم.

Common spoken changes are:

• آن → اون
• را → رو

And in casual speech, people often drop من as well:

• اون دارو رو از دکتری که دیروز دیدم خریدم.

The written version you were given is standard and correct; the colloquial version is just more conversational.