Olarul modelează vaza.

Because Romanian usually puts the definite article at the end of the noun, not as a separate word before it.

• olar = potter
• olarul = the potter

So -ul here means the for a masculine singular noun.

For the same reason: Romanian attaches the definite article to the end of the noun.

• vază = vase
• vaza = the vase

So the final -a is the feminine singular definite article.

A useful thing to notice is that the dictionary form is vază, but when it becomes definite, it changes to vaza.

Because Romanian usually uses an enclitic definite article: the article is attached to the noun itself.

So instead of saying:

• the potter
• the vase

Romanian says:

• olarul
• vaza

This is one of the big structural differences from English.

The dictionary forms are:

• olar = potter
• a modela = to shape / to model / to mould
• vază = vase

In the sentence, you see changed forms:

• olarul = the potter
• modelează = shapes / is shaping
• vaza = the vase

Modelează is the 3rd person singular present tense of a modela.

So it means:

• he/she shapes
• it shapes
• or, with a noun subject, the potter shapes

In this sentence:

• Olarul modelează vaza.
• The potter shapes the vase.

Depending on context, a modela can also mean to model, to mold, or to shape.

Mostly because of word order and meaning.

Romanian often uses Subject–Verb–Object, just like English:

• Olarul = subject
• modelează = verb
• vaza = object

So the sentence naturally reads as:

• The potter shapes the vase

Also, vaza is an inanimate direct object, so it does not need any special marker.

Because pe is often used to mark a specific direct object, especially when that object is a person or another animate being.

Examples:

• Văd fata.
• O văd pe fată. = I see the girl.

But with an inanimate noun like vaza, Romanian normally does not use pe:

• Olarul modelează vaza.

So this sentence is completely normal without pe.

Yes, Romanian word order is somewhat flexible, but Olarul modelează vaza is the most neutral and straightforward order.

If you change the order, the emphasis may change, and sometimes the meaning can become less clear.

For example:

• Olarul modelează vaza. = neutral, normal
• Vaza o modelează olarul. = The vase, the potter is shaping it; this is more marked and emphatic

For beginners, it is best to learn this sentence as a standard Subject–Verb–Object pattern.

Yes. The Romanian present tense often covers both:

• a general present: The potter shapes the vase
• an ongoing action: The potter is shaping the vase

Context tells you which one is meant.

• vaza = the vase
• o vază = a vase

So:

• Olarul modelează vaza. = The potter shapes the vase.
• Olarul modelează o vază. = The potter shapes a vase.

This is a very useful contrast to learn early in Romanian.

A rough pronunciation guide is:

• olarul ≈ oh-LA-rul
• modelează ≈ mo-de-LEA-zuh
• vaza ≈ VA-za

The Romanian letter ă is a short, neutral vowel, somewhat like the a in English sofa.

So the end of modelează is not a strong a sound; it is a softer uh-like sound.

Because the noun changes when the definite article is added.

• vază = vase
• vaza = the vase

This is just part of how that noun behaves in Romanian spelling and inflection. So yes, the change from ă to a is normal here.

Very often, yes. This is one of the core patterns in Romanian.

Examples:

• băiat = boy → băiatul = the boy
• fată = girl → fata = the girl
• olar = potter → olarul = the potter
• vază = vase → vaza = the vase

So this sentence is a good example of a very common Romanian structure.