رستورانی که نزدیک مدرسه است تمیز است.

که is the relative word that / which / who.

Here it introduces a clause that describes رستورانی:

• رستورانی = a restaurant / the restaurant
• که نزدیک مدرسه است = that is near the school

So که connects the noun to the description, just like English that in the restaurant that is near the school.

The -ی at the end is the indefinite suffix.

So:

• رستوران = restaurant
• رستورانی = a restaurant / some restaurant

A native English speaker often asks: If it has an indefinite ending, why might the translation still use "the restaurant"?

The reason is that Persian does not use a definite article like English the. A noun with a relative clause can still refer to a specific thing in context. So:

• رستورانی که نزدیک مدرسه است can be understood as a restaurant that is near the school
• but in natural English, depending on context, it may be translated as the restaurant that is near the school

So the -ی is real and important, but English may choose the because the relative clause identifies which restaurant is meant.

Because there are really two clauses, and each one has its own is.

1. که نزدیک مدرسه است
   = that is near the school

2. تمیز است
   = is clean

So the full structure is:

• [The restaurant that is near the school] [is clean].

The first است belongs to the relative clause.
The second است is the main verb of the whole sentence.

The sentence breaks down like this:

• رستورانی = restaurant
• که نزدیک مدرسه است = that is near the school
• تمیز است = is clean

So the pattern is:

• noun + relative clause + predicate adjective + copula

More literally:

• restaurant that near school is clean is

That sounds strange in English, but it is normal Persian structure.

A useful way to think of it is:

• [رستورانی که نزدیک مدرسه است] = the subject noun phrase
• [تمیز است] = what is being said about it

Persian normally has no definite article equivalent to English the.

That means Persian often leaves definiteness to:

• context
• word order
• modifiers like relative clauses

So رستورانی که نزدیک مدرسه است can be specific even without a separate word for the.

English requires a choice between a and the, but Persian often does not mark that distinction in the same way.

Yes. It is normally pronounced something like:

• nazdik-e madrese

That -e sound is usually not written in normal Persian spelling, because short vowels are often omitted in writing.

So although you see:

• نزدیک مدرسه

you usually read it as:

• نزدیکِ مدرسه
• near the school

This is very common in Persian: the written form leaves out short vowels, but speakers know they are there.

Because مدرسه is not a direct object here.

The marker را is used for specific direct objects. But in this sentence:

• مدرسه is part of the phrase نزدیک مدرسه
• that phrase means near the school
• so مدرسه is the complement of نزدیک, not an object of a verb

That is why there is no را.

تمیز is an adjective meaning clean.

In this sentence it is a predicate adjective, which means it comes with است to say what the restaurant is like:

• تمیز است = is clean

So:

• تمیز = clean
• است = is

Together they make the predicate is clean.

In everyday speech, the full written است often becomes shorter.

A common spoken version would be:

• رستورانی که نزدیک مدرسه‌ست تمیزه

You may also hear pronunciations like:

• madrese-st for مدرسه است
• tamize for تمیز است

So:

• written/formal: رستورانی که نزدیک مدرسه است تمیز است
• spoken/colloquial: رستورانی که نزدیک مدرسه‌ست تمیزه

The meaning stays the same; the spoken form is just more natural in conversation.