Mi restos en la kafejo ĝis la kunveno finiĝos.

Because resti means to stay or to remain, while esti means to be.

So:

• Mi restos = I will stay / I will remain
• Mi estos = I will be

The ending -os marks the future tense, so restos is will stay.

Kafejo is built from:

• kaf- = coffee
• -ej- = place for something
• -o = noun ending

So kafejo literally means a place for coffee, which is why it means café or coffee shop.

This kind of word-building is very common in Esperanto.

Because the sentence is describing a location, not movement.

• en la kafejo = in the café / at the café
• al la kafejo = to the café (toward it)
• en la kafejon = into the café (movement inside)

Since the speaker is staying there, Esperanto uses the simple location form: en la kafejo.

La is Esperanto’s definite article, meaning the.

So:

• la kafejo = the café
• la kunveno = the meeting

It shows that these are specific things, understood from the context. Esperanto has no separate word for a/an, so learners often notice la more than they would in English.

Ĝis means until or up to.

In this sentence, it marks the endpoint of the action. The idea is:

• I will stay in the café
• that continues up to the moment when the meeting ends

So ĝis tells you when the staying stops.

Because ĝis can introduce the clause by itself.

So ĝis la kunveno finiĝos is a normal way to say until the meeting ends.

English learners sometimes expect something like until when, but Esperanto does not need that here. Ĝis kiam is more common in direct questions such as Ĝis kiam vi restos? = Until when will you stay?

Because fini usually means to finish something, while finiĝi means to end or to come to an end.

Compare:

• Mi finos la laboron = I will finish the work
• La kunveno finiĝos = The meeting will end

A meeting usually does not finish something else; it simply ends, so finiĝos is the natural choice.

The element -iĝ- often gives the idea of becoming, getting into a state, or coming to be. It often makes a verb intransitive.

So:

• fini = finish something
• finiĝi = become finished, come to an end

In practice, finiĝi is the normal verb for to end when the subject itself is ending.

That is a very common question.

In Esperanto, it is normal to use the future tense if the action really is in the future. Since the meeting’s ending happens in the future, finiĝos makes sense.

English often uses the present tense after words like until, when, before, and after, even when the meaning is future. Esperanto does not follow that English pattern here, so ĝis la kunveno finiĝos is perfectly natural.

Not if you want exactly the same meaning.

• ĝis = until
• dum = during / while

So:

• Mi restos en la kafejo ĝis la kunveno finiĝos = I stay there up to the moment the meeting ends.
• Mi restos en la kafejo dum la kunveno = I stay there during the meeting.

Those are related ideas, but not identical. Ĝis focuses on the endpoint. Dum focuses on the period of time.