اگر تابلوی داروخانه را دیدی، بدان که نانوایی در گوشه آن خیابان است.

Because this is an ezafe construction, which links two nouns together.

• تابلو = sign / signboard
• داروخانه = pharmacy
• تابلوی داروخانه = the pharmacy’s sign or the pharmacy sign

After a word ending in a vowel like تابلو, the ezafe sound -e / -ye is usually shown in writing with ی, so you get تابلوی.

So this is not a different word; it is تابلو + ezafe.

را marks the direct object of the verb.

Here, the thing being seen is تابلوی داروخانه:

• تابلوی داروخانه را دیدی = you saw the pharmacy sign

A few useful points:

• را usually marks a specific object.
• It often does not have a direct one-word translation in English.
• It comes after the whole noun phrase, not just after the noun.

So را is telling you that the pharmacy sign is the object of دیدی.

This is a very common Persian pattern. After اگر (if), Persian often uses the simple past to talk about a possible future event.

So:

• اگر ... دیدی can mean if you see ...
• not only if you saw ...

In context, this sentence is giving directions or guidance, so دیدی is naturally understood as if you see / if you happen to see.

So the form is past, but the meaning in this kind of conditional sentence can be present/future in English.

Persian often drops subject pronouns because the verb ending already shows who the subject is.

• دیدی = you saw / you see (singular)
• بدان = know! addressed to you (singular)

So Persian does not need to say تو unless it wants extra emphasis.

This is very normal:

• اگر تابلوی داروخانه را دیدی = if you see the pharmacy sign
• not necessarily if you, specifically, see...

بدان is the imperative form of دانستن (to know).

So literally it means:

• بدان = know!

But in natural English here, it is better understood as:

• keep in mind
• be aware
• know that

This form is addressed to one person and sounds a bit standard/written or slightly formal.

Related forms:

• بدان = singular imperative
• بدانید = plural/polite imperative
• in casual speech, many speakers say بدون

So in this sentence, بدان که... means know that... / be aware that...

که introduces the clause that follows, much like English that.

• بدان که نانوایی... = know that the bakery...

In English, that is often omitted:

• Know the bakery is on the corner...

But in Persian, using که here is very natural and common.

So که is connecting:

• بدان
  to
• the information you should know

Yes, در often means in, but prepositions do not match perfectly from one language to another.

Literally:

• در گوشه آن خیابان = in the corner of that street

But in natural English, we usually say:

• on the corner of that street

So this is just a difference in idiom. Persian uses در in many places where English might use in, at, or on.

Also:

• گوشه = corner

So the whole phrase is a location phrase meaning at/on the corner of that street.

آن means that.

So:

• آن خیابان = that street

It refers to a specific street already understood from the situation. It helps make the location more definite.

Compare:

• این خیابان = this street
• آن خیابان = that street

In everyday speech, آن is often replaced by اون.

Because Persian normally puts the verb at the end of the clause.

So this part is arranged like this:

• نانوایی = the bakery
• در گوشه آن خیابان = on the corner of that street
• است = is

That gives:

• نانوایی در گوشه آن خیابان است

This is the normal Persian word order. English puts is earlier, but Persian usually saves the verb for the end.

Persian does not have a normal definite article like English the.

So Persian often leaves articles unspoken and lets context show whether something is:

• a
• the
• something general

In this sentence:

• را helps show that تابلوی داروخانه is a specific object
• آن makes خیابان clearly that street
• نانوایی is understood from context as the bakery

So Persian does not need separate words matching every English article.

It is completely natural and correct, but it sounds a bit more standard/written than very casual speech.

The slightly formal or bookish feel comes mainly from:

• اگر instead of casual اگه
• بدان instead of casual بدون
• آن instead of casual اون

A more conversational version might look something like:

• اگه تابلوی داروخونه رو دیدی، بدون که نونوایی سرِ اون خیابونه

That does not mean the original sentence is unnatural—it just sounds more like neat, standard Persian than relaxed everyday conversation.