Kiam la jako estas malseka pro pluvo, mi sekigas ĝin apud la pordo.

Kiam means when. It introduces a time clause:

• Kiam la jako estas malseka pro pluvo = When the jacket is wet because of rain

So the sentence has two parts:

• the time clause: Kiam la jako estas malseka pro pluvo
• the main clause: mi sekigas ĝin apud la pordo

A learner might compare this with se, which means if. Here the meaning is about time, not condition, so kiam is the right word.

The comma separates the subordinate clause from the main clause.

• Kiam la jako estas malseka pro pluvo, = subordinate time clause
• mi sekigas ĝin apud la pordo. = main clause

Esperanto often uses a comma before or after subordinate clauses, especially when the clause comes first. So this punctuation is very normal and helpful for clarity.

La is the definite article, meaning the.

• la jako = the jacket
• la pordo = the door

But pluvo here is being used more like an uncountable general idea: rain. In English we also usually say because of rain, not because of the rain, unless we mean some specific rain already mentioned.

So:

• pro pluvo = because of rain
• pro la pluvo would sound more like because of the rain (a specific rain)

Because malseka is an adjective describing la jako.

• malseka = wet
• malseke = wetly, which is an adverb

In la jako estas malseka, the adjective is a predicate adjective after estas, but it still describes the noun jako, so it takes -a.

Compare:

• La jako estas malseka. = The jacket is wet.
• La jako pendas malseke. = The jacket hangs wetly.
  This second one is much less natural in most situations.

Yes. Esperanto often builds words very transparently.

• seka = dry
• mal- = opposite
• malseka = wet

This is a very common pattern in Esperanto. Some other examples:

• bona = good → malbona = bad
• varma = warm → malvarma = cold
• fermi = close → malfermi = open

So malseka is a perfectly normal everyday word for wet.

Pro means because of, due to, or on account of. It shows the cause.

• malseka pro pluvo = wet because of rain

This is different from some other prepositions:

• de often shows source, possession, or agent
• el means out of/from inside
• kun means with

So pro is the natural choice when you want to explain the reason something happened.

This is one of the most important things in the sentence.

• seka = dry
• sekiĝi = to become dry
• sekigi = to make something dry, to dry something

The suffix -ig- means to cause/make.

So:

• mi sekigas ĝin = I dry it / I make it dry

If you used sekiĝas, that would mean it becomes dry. If you used sekas by itself, that is not the normal verb for to dry something in this sense.

This is a very typical Esperanto pattern:

• varmiĝi = become warm
• varmigi = make warm
• puriĝi = become clean
• purigi = clean, make clean

Because ĝin is the direct object form.

• ĝi = it
• ĝin = it as the thing being acted on

In the sentence, the speaker is drying the jacket, so the jacket is the direct object of sekigas:

• mi sekigas ĝin = I dry it

The ending -n marks the accusative, which often shows the direct object in Esperanto.

You can connect it like this:

• la jako = the jacket
• mi sekigas ĝin = I dry it

Here ĝin refers back to la jako.

Because malseka is not the direct object. It is describing the subject la jako after estas.

In other words:

• subject: la jako
• verb: estas
• adjective describing the subject: malseka

So no accusative is needed.

Compare:

• La jako estas malseka. = The jacket is wet.
• Mi portas la malsekan jakon. = I wear the wet jacket.

In the second sentence, malsekan gets -n because it is part of the direct object la malsekan jakon.

Apud means near, beside, or by.

So:

• apud la pordo = by the door / beside the door / near the door

It describes the location where the speaker dries the jacket.

It does not necessarily mean touching the door; it usually just means nearby.

Compare:

• sur la pordo = on the door
• ĉe la pordo = at the door
• apud la pordo = by / next to the door

Esperanto word order is fairly flexible, because endings show the grammatical roles.

The normal, neutral order here is:

• Kiam la jako estas malseka pro pluvo, mi sekigas ĝin apud la pordo.

But other orders are possible for emphasis, for example:

• Mi sekigas ĝin apud la pordo, kiam la jako estas malseka pro pluvo.

That said, the original version sounds very natural because it starts with the time context and then gives the main action.

Inside the clause, changing word order is also possible, but the most straightforward arrangement is usually best for learners.

Esperanto often uses the present tense for general or habitual situations, just like English can.

So this sentence can mean something like:

• Whenever the jacket is wet because of rain, I dry it by the door.

It is not necessarily happening only right now. It can describe a regular practice or general fact.

• estas = is
• sekigas = dry / am drying / do dry, depending on context

Context decides whether the meaning is immediate, repeated, or habitual.

Yes, but the meaning changes slightly.

• la jako estas malseka = the jacket is wet
• la jako malsekas = the jacket is getting wet / becoming wet

So in your sentence:

• Kiam la jako estas malseka pro pluvo focuses on the jacket already being wet
• Kiam la jako malsekas pro pluvo focuses more on the process of becoming wet because of rain

Both can make sense, but the original sentence is more direct if the idea is simply that the jacket ends up wet and then you dry it.

Yes, jako is a normal Esperanto noun meaning jacket.

Like most nouns in Esperanto, it ends in -o:

• jako = jacket
• pordo = door
• pluvo = rain

Many Esperanto words are international or familiar-looking, but they are fully adapted to Esperanto spelling and endings. So jako is exactly what you would expect: a standard noun with the noun ending -o.