Mia fratino volas traduki tiun poemon en Esperanton, ĉar ŝi tre ŝatas la originalan tekston.

Mia fratino is the subject of the sentence: it is the person doing the wanting.

In Esperanto, the -n ending marks the direct object, not the subject. So:

• mia fratino = my sister (subject)
• mian fratinon = my sister as a direct object

Here, your sister is the one who volas (wants), so mia fratino stays without -n.

Because it is the direct object of traduki.

Esperanto marks direct objects with -n, and any adjective or correlatives/determiners that go with the noun must agree with it. So:

• tiu poemo = that poem
• tiun poemon = that poem as a direct object

Both words show agreement:

• tiu → tiun
• poemo → poemon

This is very common in Esperanto:

• la bela domo
• la belan domon

This is a normal Esperanto pattern, similar to English wants to translate.

• volas = wants
• traduki = to translate / translate

After verbs like voli (to want), Esperanto usually uses the infinitive form of the second verb, which ends in -i.

So:

• Mi volas manĝi. = I want to eat.
• Ŝi volas legi. = She wants to read.
• Mia fratino volas traduki... = My sister wants to translate...

Esperanto does not use a separate word for to before the infinitive here.

With traduki, Esperanto commonly uses en to mean into a language:

• traduki en Esperanton = translate into Esperanto
• traduki en la anglan = translate into English

The -n on Esperanton is used here because en can take -n to show movement into or a change of state/direction. In this case, the poem is being rendered into Esperanto.

By contrast, al usually means to/toward a person or destination:

• Mi donis la libron al ŝi. = I gave the book to her.

So for languages after traduki, en is the standard choice.

Usually, a noun after a preposition does not take -n. But there is an important exception:

Esperanto can use -n after certain prepositions to show direction, movement, or change into something.

So:

• en Esperanto = in Esperanto
• en Esperanton = into Esperanto

Here the poem is being translated into Esperanto, so Esperanton gets -n.

A similar 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.

Ĉar means because.

It introduces a clause giving the reason for something:

• Mia fratino volas traduki tiun poemon en Esperanton, ĉar ŝi tre ŝatas la originalan tekston.
• My sister wants to translate that poem into Esperanto, because she really likes the original text.

It works much like English because.

A few more examples:

• Mi restas hejme, ĉar mi estas laca. = I’m staying home because I’m tired.
• Li lernas Esperanton, ĉar ĝi interesas lin. = He is learning Esperanto because it interests him.

Yes. Ŝi is the Esperanto pronoun for she.

Some basic pronouns are:

• mi = I
• vi = you
• li = he
• ŝi = she
• ĝi = it
• ni = we
• ili = they

Here ŝi refers back to mia fratino.

Ŝati means to like, and tre means very/really.

So:

• ŝi ŝatas = she likes
• ŝi tre ŝatas = she really likes / she likes very much

Tre modifies the verb phrase here by intensifying the liking.

Examples:

• Mi ŝatas kafon. = I like coffee.
• Mi tre ŝatas kafon. = I really like coffee.

Because tekston is the direct object of ŝatas, and originalan is an adjective describing it. In Esperanto, adjectives must agree with the nouns they modify in both number and case.

Base forms:

• originala teksto = original text

As a direct object:

• originalan tekston

Breakdown:

• originala → originalan
• teksto → tekston

This agreement is a key part of Esperanto grammar.

Yes, Esperanto word order is fairly flexible because the -n ending helps show what is the object.

The given sentence is the most neutral and natural:

• Mia fratino volas traduki tiun poemon en Esperanton, ĉar ŝi tre ŝatas la originalan tekston.

But other orders are possible, especially for emphasis:

• Tiun poemon mia fratino volas traduki en Esperanton...
• Ĉar ŝi tre ŝatas la originalan tekston, mia fratino volas traduki tiun poemon en Esperanton.

Even with changed word order, tiun poemon and la originalan tekston are still clearly objects because of -n.

Yes. Poemo means poem.

It is a noun, so it ends in -o:

• poemo = poem
• poemoj = poems
• poemon = poem as a direct object
• poemojn = poems as direct objects

This is part of Esperanto’s very regular noun system.

Because Esperanto builds words from roots and endings very systematically.

• frat- = sibling / brother-sister root
• -in- = female suffix
• -o = noun ending

So:

• frato = brother
• fratino = sister

This is a useful pattern:

• patro = father
• patrino = mother
• avo = grandfather
• avino = grandmother

A rough pronunciation guide:

• Mia = MEE-ah
• fratino = frah-TEE-no
• volas = VOH-lahs
• traduki = trah-DOO-kee
• tiun = TEE-oon
• poemon = po-EH-mon
• en = en
• Esperanton = es-peh-RAHN-ton
• ĉar = char (with ĉ like ch in church)
• ŝi = shee (with ŝ like sh)
• tre = treh
• ŝatas = SHAH-tahs
• la = lah
• originalan = oh-ree-ghee-NAH-lahn
• tekston = TEHK-ston

Special letters here:

• ĉ = ch
• ŝ = sh

Also, Esperanto stress usually falls on the second-to-last syllable:

• fraTIno
• traDUki
• EspeRANton
• origiNAlan

Sometimes, but it would not mean exactly the same thing in every context.

• la originalan tekston = the original text
• la originalo = the original / the original version

In many situations, la originalo would sound natural and slightly more idiomatic if you mean the original work as a whole. But la originalan tekston is perfectly clear and specifically refers to the text itself.

So the sentence as given is grammatical and understandable; la originalo would just be a slightly different wording.