Mia monujo ne estas en mia poŝo, do mi serĉas ĝin sur la breto.

Monujo is the ordinary Esperanto word for wallet or purse.

It is built from:

• mono = money
• -ujo = a container, holder, or place for something

So monujo literally means a container for money.

This suffix appears in other words too, for example:

• salujo = salt shaker / salt container
• inkujo = inkpot
• teujo = tea caddy / tea container

So this sentence is also a nice example of how Esperanto often builds words very logically.

Because each noun needs its own possessive word if you want to say both things belong to me.

• mia monujo = my wallet
• mia poŝo = my pocket

Esperanto does not usually let one mia automatically cover both nouns unless the structure clearly groups them together. In this sentence, the wallet and the pocket are separate noun phrases, so repeating mia is natural and normal.

In Esperanto, a possessive like mia, via, lia, and so on usually replaces the article la.

So:

• mia monujo = my wallet, not la mia monujo
• mia poŝo = my pocket, not la mia poŝo

But la breto does take la, because it means the shelf and there is no possessive there.

So the pattern is:

• mia poŝo = my pocket
• la breto = the shelf

Because ne usually goes directly before the word or part of the sentence that it negates.

Here it negates the verb:

• ne estas = is not

So:

• Mia monujo ne estas en mia poŝo = My wallet is not in my pocket

This is the normal word order for simple negation in Esperanto.

Because the prepositions match the physical relationship:

• en = in, inside
• sur = on, on top of

So:

• en mia poŝo = in my pocket
• sur la breto = on the shelf

Esperanto prepositions are usually very direct in this way.

Esperanto’s simple present tense often covers both:

• I look for
• I am looking for

So:

• mi serĉas can mean I look for or I am looking for

The context tells you which English translation sounds best. In this sentence, the natural English meaning is I am looking for it, but Esperanto does not need a special progressive form for that.

Do means so, therefore, or thus.

It shows that the second clause is a result of the first one:

• Mia monujo ne estas en mia poŝo, do mi serĉas ĝin sur la breto.
• My wallet is not in my pocket, so I am looking for it on the shelf.

It is a very common linking word in Esperanto.

Because the sentence has two full clauses:

• Mia monujo ne estas en mia poŝo
• do mi serĉas ĝin sur la breto

Putting a comma before do helps separate those clauses, just like English often does before so in a similar sentence.

Because ĝin is the direct object form of ĝi.

• ĝi = it
• ĝin = it, as a direct object

In the clause mi serĉas ĝin:

• mi = I
• serĉas = am looking for
• ĝin = it

The verb serĉi takes a direct object, so Esperanto adds -n to the pronoun.

This -n ending is called the accusative ending.

Yes. That is completely normal.

In Esperanto, ĝi is the pronoun used for a thing or object, much like English it. A wallet is an object, so ĝin is exactly what you would expect here.

So:

• la monujo = the wallet
• ĝin = it

Because this sentence describes location, not movement toward a place.

• sur la breto = on the shelf
• sur la breton = onto the shelf

Here the speaker is looking for the wallet on the shelf, so plain sur la breto is correct.

A useful contrast:

• La libro estas sur la tablo. = The book is on the table.
• Mi metas la libron sur la tablon. = I put the book onto the table.

So -n can help show direction or motion to a place, but that is not what is happening in your sentence.

Because Esperanto normally states the subject in each clause.

So:

• Mia monujo ne estas en mia poŝo
• do mi serĉas ĝin sur la breto

Even though English also repeats I here, this is worth noticing because some languages allow the subject pronoun to be omitted more often. Esperanto usually does not do that in ordinary sentences.

A rough English-style guide is:

• poŝo ≈ PO-sho
• monujo ≈ mo-NU-yo
• breto ≈ BRE-to

A few helpful points:

• ŝ sounds like English sh
• j sounds like English y
• stress in Esperanto normally falls on the next-to-last syllable

So:

• PO-ŝo
• mo-NU-jo
• BRE-to

That regular stress pattern is one of the nice things about Esperanto pronunciation.