La katalogo montras haveblan ekzempleron en alia sekcio.

Because the whole phrase is the direct object of montras (shows).

In Esperanto, the direct object takes -n, and any adjective that describes that noun must agree with it:

• ekzemplero → ekzempleron
• havebla → haveblan

So:

• La katalogo montras ekzempleron = The catalog shows a copy
• La katalogo montras haveblan ekzempleron = The catalog shows an available copy

The adjective and noun match in ending.

haveblan comes from:

• havi = to have
• -ebl- = able to be / possible to
• -a = adjective ending
• -n = accusative ending

So:

• havebla literally means able to be had
• in natural English, that usually means available or obtainable

Then haveblan is just the accusative form agreeing with ekzempleron.

It is understandable and correctly formed, but many speakers might more often use words like disponebla for available, depending on context.

So havebla ekzemplero is grammatical and clear, but in some situations a learner may also encounter:

• disponebla ekzemplero = available copy
• sometimes other phrasing depending on what kind of availability is meant

Still, havebla is a good example of how Esperanto builds words very productively.

Not usually. This is an important vocabulary point.

• ekzemplo = example
• ekzemplero = copy / specimen / individual item

In this sentence, ekzemplero means something like a copy of a book, document, or item in a catalog.

So havebla ekzemplero is an available copy, not an available example.

Because en can express either:

• location → no -n
• movement into somewhere → usually -n

Here the meaning is location: the copy is in another section, not moving into another section.

So:

• en alia sekcio = in another section
• en alian sekcion = into another section

Since this sentence describes where the copy is, sekcio does not take -n.

Because alia describes sekcio, and sekcio is not the direct object here.

The direct object is haveblan ekzempleron, so that phrase gets -n.

But en alia sekcio is a prepositional phrase showing location, so both words stay without -n:

• alia sekcio = another section
• en alia sekcio = in another section

Esperanto has:

• la = the
• no separate word for a/an

So:

• La katalogo = The catalog
• ekzempleron can mean a copy or just copy, depending on context
• alia sekcio = another section

Esperanto does not require an article before every noun. If the meaning is indefinite, it often simply uses no article.

Yes, Esperanto word order is fairly flexible because endings show the grammar.

The neutral order here is:

• La katalogo montras haveblan ekzempleron en alia sekcio.

But other orders are possible for emphasis, for example:

• En alia sekcio la katalogo montras haveblan ekzempleron.
• Haveblan ekzempleron la katalogo montras en alia sekcio.

These are still understandable because -n marks the object.
However, the original order is the most straightforward and natural for learners.

It is a prepositional phrase telling you the location.

Breakdown:

• en = in
• alia = other / another
• sekcio = section

Together: in another section

It modifies the situation described by the sentence, telling where the available copy is shown as being.

Yes. Alia can often be translated as either other or another, depending on context.

Examples:

• alia libro = another book / a different book
• alia sekcio = another section / a different section

In this sentence, another section is usually the most natural English translation.

Because -as marks the present tense in Esperanto.

• montri = to show
• montras = shows / is showing

So La katalogo montras... means The catalog shows...

If you changed the tense:

• montris = showed
• montros = will show

Usually yes, or very close. Katalogo means catalog / catalogue.

In this sentence it refers to some system or listing that indicates where an available copy can be found. Depending on context, it could be:

• a library catalog
• an inventory catalog
• a database-style listing

So the word is straightforward for English speakers, but the exact real-world meaning depends on context.

A useful breakdown is:

• La = the
• katalogo = catalog
• montras = shows
• haveblan = available
• ekzempleron = copy
• en = in
• alia = another
• sekcio = section

So the structure is:

• The catalog
• shows
• an available copy
• in another section

This is a good example of how Esperanto uses endings to show grammar very clearly.