Learn Hardcore Turkish: Otopark doluysa, biz sokakta yer arıyoruz. - If the parking lot is full, we look for a spot on the street.

So otopark doluysa literally means “if the parking lot is full” or “when the parking lot is full”.
The -sa / -se ending is how Turkish forms many if-clauses directly on adjectives, verbs, or nouns, without using a separate word like “if”.

Why is it doluysa and not doluyorsa?

Because:

doluysa = dolu (full) + -sa (if) → if it is full
doluyorsa would be dolu
- yor (progressive) + -sa (if) → something like “if it is becoming full / if it is in the process of getting full”, which is not what is meant here.

In this sentence, we are talking about the state of the parking lot (full or not), not the ongoing process of filling up, so the simple doluysa is correct.

What is the -y- in doluysa?

The -y- is a buffer consonant used to avoid two vowels coming together.

Stem: dolu (ends in a vowel)
Suffix: -sa (starts with a vowel)

dolu + sa would give dolusa, which is hard to pronounce, so Turkish inserts a buffer consonant:
dolu + y + sa → doluysa.

This same buffer -y- appears in many places in Turkish (e.g. o + -a → ona, dolu + -um → doluyum, etc.).

Could we write otopark doluysa as otopark dolu ise?

Yes.

doluysa is the merged / contracted form.
dolu ise is the separate / more formal form.

Both mean “if (it) is full”, and both are correct.
In everyday speech, the merged form (doluysa, boşsa, ucuzsa etc.) is very common.

Why is it -sa and not -se in doluysa?

Because of vowel harmony.

The conditional ending has two basic forms:

-sa after a back vowel (a, ı, o, u)
-se after a front vowel (e, i, ö, ü)

The last vowel in dolu is u (a back vowel), so we use -sa:
dolu + y + sa → doluysa.

If the word ended in a front vowel, you’d get -se, for example:

temiz → temizse (if it is clean)
mümkün → mümkünse (if it is possible)

Why is biz used here? Can it be omitted?

In Turkish, subject pronouns (like ben, sen, biz) are usually optional, because the verb ending already shows the person.

arıyoruz already tells you it’s “we are searching” (1st person plural).

So both are possible:

Biz sokakta yer arıyoruz.
Sokakta yer arıyoruz.

Using biz often adds a bit of emphasis or clarity, especially in speech or when contrasting:
Otopark doluysa, biz sokakta yer arıyoruz, onlar ise eve dönüyor.
(If the parking lot is full, we look for a place in the street, but they go back home.)

What tense is arıyoruz, and why is it used here instead of ararız?

Arıyoruz is the present continuous (şimdiki zaman):

Verb stem: ara- (to search)
Progressive marker: -ıyor → with vowel harmony becomes -ıyor / -iyor / -uyor / -üyor
Here: ara + ıyor → arıyor
1st person plural: -uz
→ arıyoruz

So arıyoruz = “we are searching / we look for”.

In English, this type of if-clause usually uses a simple present:
“If the parking lot is full, we look for a place on the street.”

In Turkish, both can be used:

arıyoruz (present continuous) – very common in spoken language, can describe usual behavior.
ararız (simple present / aorist) – more generic or habitual, like a rule.

Both can work here, but arıyoruz sounds very natural in everyday speech to describe what you typically do in that situation.

Why is it sokakta and not sokakda?

This is about the locative suffix (-da / -de / -ta / -te) and consonant harmony.

The locative suffix has 4 forms: -da, -de, -ta, -te
After a voiced consonant or vowel → -da / -de
After a voiceless consonant (p, ç, t, k, f, h, s, ş) → -ta / -te

Sokak ends with k, which is voiceless, so we use -ta:

sokak + ta → sokakta = “in/on the street”.

If the word were ev (house), you’d say:

ev + de → evde (at home), because v is voiced.

What exactly does yer mean in sokakta yer arıyoruz?

Literally, yer means “place”.

In this context, sokakta yer arıyoruz is understood as “we look for a (parking) place in the street”, i.e. an empty spot to park the car.

You could also make it more explicit:

sokakta park yeri arıyoruz – we look for a parking place in the street.

But in everyday speech, just yer arıyoruz is often enough; from the context of otopark, listeners automatically understand “parking space”.

Why is there no word like “the” or “a” before otopark or yer?

Turkish does not use articles like English “the” or “a/an”.

otopark can mean “a parking lot” or “the parking lot”, depending on context.
yer can mean “a place” / “some space”.

Definiteness and indefiniteness are understood from the context and word order, not from a separate article word.

Why is the word order biz sokakta yer arıyoruz and not biz yer sokakta arıyoruz?

Turkish has a basic SOV (Subject–Object–Verb) word order:

Subject: biz
Place expression (adverbial): sokakta (in the street)
Object: yer (a place)
Verb: arıyoruz

So biz sokakta yer arıyoruz follows the natural pattern:

Subject – (adverbials) – Object – Verb

You could move things for emphasis, but biz yer sokakta arıyoruz sounds awkward and unnatural here.
The normal way to say “We look for a place in the street” is exactly biz sokakta yer arıyoruz.