بله، نقشه در چمدان من است و آن را فراموش نکردم.

A careful transliteration is:

bale, naqše dar chamadân-e man ast va ân râ farâmuš nakardam.

A few helpful pronunciation notes:

• نقشه = naqše
• چمدان من is pronounced chamadân-e man because of a hidden ezafe sound
• آن را is often pronounced more casually as un-o in speech
• فراموش نکردم = farâmuš nakardam

So in everyday speech, the whole sentence may sound less formal than it looks in writing.

Yes. بله means yes.

For an English speaker, the main thing to know is that:

• بله is polite, neutral, or somewhat formal
• in casual speech, people often say آره

So this sentence starts in a slightly careful or polite way. It is not unusual, especially in writing or clear speech.

Persian uses a linker called ezafe between a noun and what describes or possesses it.

So:

• چمدان من is pronounced chamadân-e man
• literally, it is something like suitcase-of me
• that is how Persian says my suitcase

The important point is that the -e sound is usually not written in normal Persian script, but native speakers know it is there.

Yes.

Both mean my suitcase:

• چمدان من = my suitcase
• چمدانم = my suitcase

The second one uses the attached possessive ending -م.

So you could also say:

نقشه در چمدانم است

That is often more natural and compact.

Because Persian usually puts the verb at or near the end of the clause.

So instead of English word order:

• The map is in my suitcase

Persian prefers:

• The map in my suitcase is
• نقشه در چمدان من است

This verb-final tendency is one of the biggest structural differences from English.

Yes. در means in, and it is completely correct here.

But there is also a register difference:

• در sounds more formal or written
• توی or تو is very common in everyday speech for physical location

So these are both possible:

• نقشه در چمدان من است — more formal/written
• نقشه توی چمدانم است / هست — more conversational

Here آن را means it.

The two parts do different jobs:

• آن = that / it
• را = the direct object marker

So آن را فراموش نکردم literally means something like:

• I did not forget that/it

For English speakers, را is important because English does not have a separate object marker like this.

Because را marks a specific direct object.

In standard Persian, when the object is definite or specific, را is normally used. Since it refers to a specific thing already known — the map — را is expected.

So:

• آن را فراموش نکردم = standard, clear
• آن فراموش نکردم = not standard here

This is one of the most common grammar points learners need to get used to.

Because Persian, like English, often uses a pronoun to avoid repetition.

So after mentioning نقشه, it is natural to refer back to it with آن را = it.

You could repeat the noun:

• نقشه را فراموش نکردم

That is also grammatical. It may sound a little more explicit or emphatic, depending on context.

Because فراموش کردن is a compound verb.

It is made of:

• فراموش = forgetfulness / forgotten
• کردن = to do

Together, فراموش کردن means to forget.

In Persian compound verbs, tense and negation usually go on the light verb, which here is کردن.

So:

• فراموش کردم = I forgot
• فراموش نکردم = I did not forget

This pattern is extremely common in Persian.

A useful breakdown is:

• بله = yes
• نقشه = the map
• در چمدان من = in my suitcase
• است = is
• و = and
• آن را = it
• فراموش نکردم = I did not forget

So the structure is roughly:

• Yes, [the map] [in my suitcase] [is], and [it] [did not forget].

That sounds odd in English, but it reflects normal Persian word order pretty well.

Yes, it is grammatical and clear, but it sounds somewhat formal.

In more everyday speech, a speaker might say something like:

بله، نقشه توی چمدانم هست و فراموشش نکردم.

A few differences there:

• توی instead of در for everyday in
• چمدانم instead of چمدان من
• فراموشش نکردم instead of آن را فراموش نکردم
• هست is often more common than careful written است in speech

So your original sentence is good Persian, especially in a more careful or written style.