La dua semestro finiĝos en junio, sed mia fratino restos en la urbo ĝis julio pro sia laboro.

La is the definite article, meaning the.

So La dua semestro means the second semester.

Esperanto often uses la when talking about a specific thing already understood in context. In English, we would also normally say the second semester, not just second semester, unless we were speaking in a more abbreviated style.

• dua semestro = second semester
• la dua semestro = the second semester

Dua means second.

Ordinal numbers in Esperanto are made by adding -a to the basic number:

• unu = one → unua = first
• du = two → dua = second
• tri = three → tria = third

Because -a is an adjective ending, ordinal numbers behave like adjectives and describe nouns:

• dua semestro = second semester
• tria tago = third day

Semestro means semester or half-year term, especially in an academic context.

It is a regular noun:

• semestro = semester
• semestroj = semesters

In the sentence, La dua semestro means The second semester.

Finiĝos comes from:

• fini = to finish, to end
• -iĝ- = to become, to get into a state, or to happen by itself
• -os = future tense

So:

• fini = to finish something
• finiĝi = to finish / to come to an end

And:

• finiĝos = will finish / will end

This is a very common Esperanto pattern:

• fermi = to close something
• fermiĝi = to close, to become closed

So La dua semestro finiĝos en junio means The second semester will end in June.

Because the semester is not actively finishing something else. Instead, it itself comes to an end.

Compare:

• Mi finos la laboron. = I will finish the work.
  • Here, mi is acting on la laboron.
• La laboro finiĝos morgaŭ. = The work will finish / be completed tomorrow.
  • Here, the work itself comes to an end.

So La dua semestro finiĝos is natural because the semester is ending, not ending something else.

En junio means in June.

For months, seasons, and many time expressions, Esperanto commonly uses en:

• en junio = in June
• en julio = in July
• en somero = in summer

Je is more of a general-purpose preposition used when no more specific preposition fits well. Here, en is the normal choice.

Month names normally do not take la unless there is some special reason.

So:

• en junio = in June
• ĝis julio = until July

This is similar to English, where we usually say in June, not in the June.

Sed means but.

It connects two contrasting ideas:

• La dua semestro finiĝos en junio = The second semester will end in June
• sed mia fratino restos en la urbo ĝis julio = but my sister will stay in the city until July

So sed is a very common conjunction for contrast.

It can mean both stay and remain, depending on context.

• resti = to stay, to remain
• restos = will stay, will remain

In this sentence, mia fratino restos en la urbo ĝis julio naturally means my sister will stay in the city until July.

Examples:

• Mi restos hejme. = I will stay home.
• Nur unu pomo restas. = Only one apple remains.

Because en la urbo describes location, not movement.

• en = in
• al = to, toward

So:

• restos en la urbo = will stay in the city
• iros al la urbo = will go to the city

Since your sister is not moving toward the city in this part of the sentence, but staying there, en is correct.

La urbo means the city.

The article is used because the speaker likely has a specific city in mind, one known from context. This is very natural in Esperanto, just as in English:

• en urbo would sound more like in a city
• en la urbo = in the city

So the sentence refers to a particular city already understood.

Ĝis means until, up to, or as far as in time or space.

So:

• ĝis julio = until July

It marks the endpoint of the staying:

• restos en la urbo ĝis julio = will stay in the city until July

Other examples:

• ĝis morgaŭ = until tomorrow
• ĝis la fino = until the end

Pro means because of.

So:

• pro sia laboro = because of her work

It gives the reason why the sister will stay until July.

Compare:

• Mi malfruis pro la pluvo. = I was late because of the rain.
• Ŝi restas pro sia laboro. = She is staying because of her work.

This is one of the most important Esperanto grammar points.

Sia is a reflexive possessive adjective. It refers back to the subject of the clause.

In the clause:

mia fratino restos en la urbo ĝis julio pro sia laboro

the subject is mia fratino, so sia laboro means her own work.

Why not ŝia laboro? Because ŝia would usually refer to some other female person, not the subject herself.

Compare:

• Maria amas sian hundon. = Maria loves her own dog.
• Maria amas ŝian hundon. = Maria loves her dog — some other woman's dog.

So in your sentence, sia laboro correctly shows that it is the sister’s own job.

It refers to the subject of its own clause, not automatically the subject of the entire sentence.

Here the relevant clause is:

mia fratino restos en la urbo ĝis julio pro sia laboro

The subject of that clause is mia fratino, so sia refers to mia fratino.

This matters in more complex sentences. You always look for the subject of the clause where sia appears.

Because there is no direct object here.

The sentence mostly uses:

• subjects: la dua semestro, mia fratino
• prepositional phrases: en junio, en la urbo, ĝis julio, pro sia laboro

The accusative -n is usually used for direct objects, and sometimes for motion toward something or certain time expressions. None of those are needed here.

For example:

• Mi finos la semestron. = I will finish the semester.
  • la semestron has -n because it is a direct object.

But:

• La semestro finiĝos. = The semester will end.
  • no direct object, so no -n

Esperanto word order is fairly flexible, but the given order is the most natural and clear.

Current sentence: La dua semestro finiĝos en junio, sed mia fratino restos en la urbo ĝis julio pro sia laboro.

You could move some phrases for emphasis, for example:

• Pro sia laboro mia fratino restos en la urbo ĝis julio.
• Mia fratino restos ĝis julio en la urbo pro sia laboro.

These are still understandable, but the original order sounds very normal and straightforward.

A rough English-friendly pronunciation would be:

lah DOO-ah seh-MES-troh fee-nee-JOHSS en yoo-NEE-oh, sed MEE-ah frah-TEE-noh RES-tohs en lah OOR-boh ees-TEE yoo-LEE-oh proh SEE-ah lah-BOH-roh

A few helpful points:

• j sounds like English y
• ĝ sounds like the j in judge
• stress is always on the second-to-last syllable:
  • seMEs tro
  • juNIo
  • fraTIno
  • laBOro

Yes.

• frato = brother
• -in- = female suffix
• fratino = sister

This is a very productive Esperanto pattern:

• patro = father, parent in some contexts
• patrino = mother
• kato = cat
• katino = female cat

So mia fratino literally means my sister.

It has two main clauses joined by sed:

1. La dua semestro finiĝos en junio

   • subject: La dua semestro
   • verb: finiĝos
   • time phrase: en junio

2. mia fratino restos en la urbo ĝis julio pro sia laboro

   • subject: mia fratino
   • verb: restos
   • place: en la urbo
   • time limit: ĝis julio
   • reason: pro sia laboro

So the sentence is basically:

[The second semester will end in June], but [my sister will stay in the city until July because of her work].