La modelo kontrolas la fonon kaj la kadron.

The -n ending marks the direct object in Esperanto. These are the things being controlled, so they take -n.

• la modelo = the subject, the thing doing the action
• kontrolas = controls / is controlling
• la fonon and la kadron = the objects, the things receiving the action

This is called the accusative ending.

Because modelo is the subject, not the object. In Esperanto, the subject normally has no special ending, while the direct object takes -n.

So:

• La modelo = the model does the action
• la fonon kaj la kadron = what the action is done to

-as is the Esperanto verb ending for the present tense.

So kontrolas means controls, is controlling, or sometimes just does control, depending on context.

Esperanto verbs are very regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command / wish

La is the Esperanto definite article, equivalent to English the.

It appears before each noun here because each noun phrase is definite:

• la modelo
• la fonon
• la kadron

Esperanto often repeats la where English would too. You normally use it separately with each noun unless the structure clearly lets one article cover multiple nouns.

Usually, the most natural form is la fonon kaj la kadron, repeating la before both nouns.

You may sometimes see one article covering coordinated nouns, but with a sentence like this, repeating la is clearer and more standard for learners.

Also, remember that both objects still need -n:

• la fonon
• la kadron

In Esperanto, nouns normally end in -o.

So:

• modelo = a noun
• fono = a noun
• kadro = a noun

When a noun is a direct object, you add -n, giving:

• fono → fonon
• kadro → kadron

Not completely. Because Esperanto marks direct objects with -n, word order is more flexible than in English.

The basic order here is:

• subject + verb + object

So La modelo kontrolas la fonon kaj la kadron is the most straightforward version.

But other orders are possible, especially for emphasis, because fonon and kadron are clearly marked as objects by -n.

Kaj means and. It joins the two objects:

• la fonon
• la kadron

So the verb applies to both of them.

Esperanto spelling is very regular. kontrolas is pronounced roughly like kon-TRO-las, with the stress on the second-to-last syllable.

A few helpful pronunciation points:

• Stress in Esperanto is almost always on the second-to-last syllable
• Each vowel is pronounced clearly
• Letters are usually pronounced consistently

So:

• mo-DE-lo
• kon-TRO-las
• FO-non
• KAJ
• KA-dron

Yes, but it would change the sense.

Without la, the nouns would be less specifically identified:

• Modelo kontrolas fonon kaj kadron would sound more like talking about a model, a background, and a frame in a general way.

With la, the sentence refers to specific, known things:

• the model
• the background
• the frame

Because Esperanto verbs do not change according to the subject.

In English, you have:

• I control
• you control
• he/she/it controls

In Esperanto, it stays the same:

• mi kontrolas
• vi kontrolas
• li/ŝi/ĝi kontrolas

That regularity is one of the simplest parts of Esperanto grammar.