La telefono estas inter la libro kaj la taso.

La is the definite article, meaning the.

So:

• la telefono = the phone
• telefono = a phone / phone depending on context

Esperanto has la for the, but it does not have a separate word for a/an. If you leave out la, the noun is usually indefinite or more general.

In Esperanto, the article usually goes directly before each noun it belongs to.

So:

• la telefono = the phone
• la libro = the book
• la taso = the cup

English sometimes works similarly, but Esperanto is very regular about it. If all three nouns are specific, each one normally gets its own la.

Estas means is / are / am.

It is the present tense form of the verb esti = to be.

So:

• La telefono estas... = The phone is...

Esperanto verbs do not change according to the subject:

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

So estas is always the present-tense form, no matter who or what the subject is.

Inter means between or sometimes among, depending on context.

In this sentence:

• inter la libro kaj la taso = between the book and the cup

Because there are two things named after it, between is the natural translation here.

Kaj means and.

So:

• la libro kaj la taso = the book and the cup

This joins the two nouns that define the location of the phone.

The -n ending in Esperanto is usually used for:

1. the direct object
2. motion toward something in some expressions

In this sentence, la libro and la taso are not direct objects. They are part of a prepositional phrase after inter.

So you say:

• inter la libro kaj la taso

not because of movement, but because the phone is located there.

If the sentence involved motion, Esperanto might use -n in some cases, but not here.

In Esperanto, nouns end in -o.

So:

• telefono = phone
• libro = book
• taso = cup

This makes word class very easy to recognize. If you see -o, it is a noun.

Yes, it is an international-style Esperanto word based on the same root found in many European languages.

That is common in Esperanto. Many words are designed to be recognizable:

• telefono = telephone/phone
• libro = book
• taso = cup

Even when a word looks familiar, it still follows normal Esperanto grammar, so telefono is treated just like any other noun.

This is the most straightforward word order:

• La telefono = subject
• estas = verb
• inter la libro kaj la taso = location phrase

So it is basically:

The phone + is + between the book and the cup

Esperanto word order is fairly flexible, but this is the most neutral and natural order for a simple statement.

In a normal complete sentence like this, no. You need the verb.

So:

• La telefono estas inter la libro kaj la taso. = correct

Without estas, you would not have a full standard sentence.

Esperanto pronunciation is very regular. telefono is pronounced roughly:

te-le-FO-no

Each vowel is pronounced clearly, and the stress is on the second-to-last syllable. That is a general Esperanto rule.

The words in the sentence are roughly:

• La = lah
• telefono = te-le-FO-no
• estas = ES-tahs
• inter = IN-ter
• libro = LEE-bro
• kaj = like kai in aisle-type vowel quality, roughly kai
• taso = TAH-so

No. La never changes.

It always means the, whether the noun is:

• singular or plural
• masculine, feminine, or neuter in meaning

So Esperanto is simpler than many European languages in this way.

Examples:

• la telefono = the phone
• la telefonoj = the phones
• la libro = the book
• la libroj = the books

The article stays la every time.

Yes. Inter can mean both between and among, depending on context.

For example:

• inter du seĝoj = between two chairs
• inter amikoj = among friends

In your sentence, since only two objects are mentioned, English naturally uses between.