La strekkodo estas sur la libro.

La is the Esperanto definite article, meaning the.

So:

• la strekkodo = the barcode
• la libro = the book

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

A learner might also notice that Esperanto often uses la a little differently from English depending on context, but in a simple sentence like this, it works very much like the.

Strekkodo is a compound word:

• strek = line, stripe
• kodo = code

So strekkodo literally means stripe-code or bar code, which is why it means barcode.

Compound words are very common in Esperanto. Usually, the main idea comes at the end, so strekkodo is a kind of kodo.

No. In Esperanto, verbs do not change according to person or number.

So:

• mi estas = I am
• vi estas = you are
• li estas = he is
• ili estas = they are

The ending -as always marks the present tense.

That makes estas very easy: it simply means is / am / are, depending on the subject.

Sur is the preposition meaning on.

So:

• sur la libro = on the book

It is used for physical contact with the top surface of something, just like English on in many cases.

Examples:

• La taso estas sur la tablo. = The cup is on the table.
• La kato estas sur la seĝo. = The cat is on the chair.

Because there is no direct object here, and sur la libro expresses location, not motion toward something.

In Esperanto, -n is commonly used for:

1. the direct object
2. direction toward a place

Here:

• La strekkodo is the subject
• estas is the verb
• sur la libro tells where it is

So no -n is needed.

Compare:

• La strekkodo estas sur la libro. = The barcode is on the book.
  
  • location
• Mi metas la strekkodon sur la libron. = I put the barcode onto the book.
  
  • motion toward the surface, so libron gets -n

Yes, but it means something slightly different in focus.

• La strekkodo estas sur la libro. = The barcode is on the book.
  
  • Focus: the barcode and its location
• La libro havas strekkodon. = The book has a barcode.
  
  • Focus: the book possesses a barcode

Both can describe a similar situation, but they are not identical in emphasis.

Not completely. Esperanto word order is fairly flexible, although some orders sound more natural than others.

The most neutral order is:

• La strekkodo estas sur la libro.

You could also say:

• Sur la libro estas la strekkodo.

That version puts more emphasis on the location, something like On the book is the barcode.

Because Esperanto marks grammar clearly with endings and prepositions, word order can be moved around more easily than in English.

A simple pronunciation guide is:

strek-KO-do

A few points:

• stress is on the second-to-last syllable: KO
• every vowel is pronounced clearly
• e is like e in bet
• o is like o in for or a pure o sound, depending on accent

Broken into syllables:

• strek
• ko
• do

So: strek-KO-do

In Esperanto, nouns normally end in -o.

So:

• libro = book
• kodo = code
• strekkodo = barcode

This is one of the basic patterns of the language:

• -o = noun
• -a = adjective
• -e = adverb
• -i = infinitive verb

Because of this system, Esperanto words are often easy to identify by their endings.

Yes. The plural of a noun is made with -j.

So:

• strekkodo = barcode
• strekkodoj = barcodes

That gives:

• La strekkodoj estas sur la libro. = The barcodes are on the book.

Notice that the verb still stays estas. It does not change in the plural.

If both nouns were plural, you could say:

• La strekkodoj estas sur la libroj. = The barcodes are on the books.

Grammatically, Esperanto sometimes allows nouns without la, but in this sentence that would usually sound unnatural unless you mean something very non-specific.

• La strekkodo estas sur la libro. = The barcode is on the book.
  
  • a specific barcode and a specific book
• Strekkodo estas sur libro.
  
  • sounds like A barcode is on a book or a very generic statement, but not the normal way to say it

If you want the indefinite idea a, Esperanto often simply uses no article:

• Strekkodo estas sur libro.

But in real usage, many speakers would prefer a more natural sentence such as:

• Estas strekkodo sur libro.
• Sur libro estas strekkodo.

Still, for the original sentence, la is the normal and clear choice.