Mi lasos la pakon ĉe la pordo, se vi ne estos hejme.

The ending -os marks the future tense in Esperanto.

• lasi = to leave, to let
• lasos = will leave

So Mi lasos means I will leave. Esperanto verb endings are very regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command / volitive
• -i = infinitive

Because la pakon is the direct object of the verb lasos.

In Esperanto, the direct object usually takes the ending -n:

• la pako = the package
• mi lasos la pakon = I will leave the package

This -n ending is called the accusative ending. It shows what is being acted on.

la is the definite article, meaning the.

So:

• pakon = a package / package
• la pakon = the package

It is used when the speaker means a specific package, not just any package. In Esperanto, la does not change for gender, number, or case.

ĉe usually means at, by, or at the place of.

In this sentence, ĉe la pordo means something like:

• at the door
• by the door

It is a general location word. It does not necessarily mean directly touching the door; it just places the package in that area.

Because en la pordo would literally mean in the door, which is not the intended idea.

Compare:

• ĉe la pordo = at/by the door
• apud la pordo = next to/beside the door
• en la pordo = in the door

Here, ĉe is the natural choice for leaving something at the door.

Because the sentence refers to a future situation.

• estas = is / are
• estos = will be

Since the speaker is talking about what will happen later, Esperanto uses the future tense in both parts:

• Mi lasos... = I will leave...
• se vi ne estos hejme = if you will not be home / if you are not home

Unlike English, Esperanto does not avoid the future tense in if clauses when the meaning is future.

hejme means at home.

It is an adverb, built from hejmo (home) with the adverb ending -e:

• hejmo = home
• hejme = at home

Esperanto often uses adverb forms like this for locations or states:

• hejme = at home
• lerneje = at school
• urbe = in the city / in town

en la hejmo would mean something more literal like in the home/house, which is less natural here. For the ordinary idea be home, esti hejme is the normal expression.

In Esperanto, ne normally goes directly before the word it negates. Here it negates the verb phrase:

• vi estos hejme = you will be home
• vi ne estos hejme = you will not be home

That is the standard and most natural placement.

vi can mean:

• you singular
• you plural
• formal you
• informal you

In normal modern Esperanto, vi is used for all of these. There is a word ci for singular informal you, but it is rare and usually not used in everyday Esperanto.

So vi is the normal choice.

Yes. Esperanto allows that easily.

You can say:

• Mi lasos la pakon ĉe la pordo, se vi ne estos hejme.
• Se vi ne estos hejme, mi lasos la pakon ĉe la pordo.

Both mean the same thing. The difference is mainly emphasis and style. Starting with se puts the condition first.

Because se vi ne estos hejme is a subordinate clause.

In standard Esperanto writing, clauses introduced by words like se, ke, kiam, and similar conjunctions are often separated by commas. So the comma here is normal and expected.

No, not exactly. In this sentence, lasi means leave something somewhere or let something remain.

So:

• Mi lasos la pakon ĉe la pordo = I will leave the package at the door

If you mean leave in the sense of go away/depart, Esperanto often uses a different verb, such as foriri.

So a learner should notice that English leave can correspond to different Esperanto verbs depending on the meaning.

ĉ is pronounced like ch in church.

So ĉe sounds roughly like cheh.

More specifically:

• ĉ = English ch
• e = a pure vowel, like e in bet but without turning into a diphthong

So ĉe is approximately cheh.