Mardon mi iros al la biblioteko post la laboro.

In Esperanto, -n is not only for direct objects. It can also mark time without a preposition.

So Mardon means on Tuesday.

This is a very common Esperanto pattern:

• Lundon = on Monday
• Mardon = on Tuesday
• Venontan semajnon = next week

So in this sentence, Mardon mi iros... means On Tuesday, I will go...

You may also see marde, which is another way to express on Tuesday.
A learner-friendly way to think of the difference is:

• mardon = on Tuesday, as a time point
• marde = on Tuesday / Tuesdays, more adverb-like

Both can work, but mardon is very normal here.

Iros is the future tense of iri = to go.

Esperanto verb endings are very regular:

• iras = go / am going
• iris = went
• iros = will go
• irus = would go
• iru = go!
• iri = to go

So:

• mi iros = I will go

Because the sentence talks about something happening in the future, Esperanto uses -os.

Al means to or toward, so it shows destination.

• al la biblioteko = to the library

By contrast, en means in or inside:

• en la biblioteko = in the library

So:

• Mi iros al la biblioteko = I will go to the library
• Mi estos en la biblioteko = I will be in the library

If you wanted to emphasize movement into the library, you could say en la bibliotekon, but al la biblioteko is the most natural basic way to say to the library.

La is the Esperanto word for the.

So:

• la biblioteko = the library
• biblioteko = a library / library depending on context

Esperanto has only one definite article: la. It does not change for gender, number, or case in form.

In this sentence, la biblioteko suggests a specific library, or at least a library understood from the situation.

Literally, post la laboro means after the work.

But in normal usage, it often corresponds to English after work.

Here is the breakdown:

• post = after
• la laboro = the work

So the phrase refers to the time after someone's work or workday is finished.

English often leaves out the in expressions like after work, but Esperanto commonly uses la in phrases like this when the situation is understood.

Because post is a preposition, and its noun normally does not take -n just because it follows the preposition.

So:

• post la laboro = after work

The -n ending is not needed here.

A useful rule for beginners is:

• after a normal preposition like al, post, en, kun, sur, the noun usually does not take -n
• unless there is a special reason, such as showing direction with certain expressions

Here, post la laboro is just an ordinary prepositional phrase.

Yes, a little. Esperanto word order is fairly flexible, and putting Mardon first gives it emphasis.

So:

• Mardon mi iros al la biblioteko post la laboro.
• Mi iros al la biblioteko mardon post la laboro.

Both are grammatical.

Starting with Mardon is like saying:

• On Tuesday, I will go to the library after work.

So the sentence begins with the time expression for emphasis or topic.

Yes. That is also correct.

• Mardon uses the accusative of time
• marde uses an adverb form

Both can mean on Tuesday.

For a beginner, it is enough to know that Esperanto often allows both patterns:

• Mardon mi iros...
• Marde mi iros...

The version with Mardon is especially useful because it teaches the common time expression with -n pattern.

No. Esperanto verbs show tense, but they do not show person.

So iros only means will go. It does not tell you whether the subject is:

• I
• you
• he
• she
• we
• they

That is why the pronoun is needed:

• mi iros = I will go
• vi iros = you will go
• ili iros = they will go

So mi is necessary unless the subject is already very clear from context.

In most ordinary contexts, it means after work, that is, after the work period or workday.

So this sentence is normally understood as:

• On Tuesday I will go to the library after work.

It usually does not mean after my career/job is over.

Context decides the exact nuance, but the everyday reading is the same one an English speaker would expect from after work.