Engelli park yeri trafik işaretiyle gösterilmiş.

Here engelli means disabled or for disabled people.

In Turkish, engelli can be:

• an adjective: disabled
• a noun: a disabled person

In engelli park yeri, it describes the type of parking space: a parking place intended for disabled people.

Because park yeri is a very common Turkish noun-compound pattern.

It is made like this:

• park = parking
• yer = place
• yeri = its place / place for

So park yeri literally means parking place or parking spot.

This is an indefinite noun compound in Turkish:

• otobüs durağı = bus stop
• okul kapısı = school gate
• park yeri = parking place

The second noun often takes a possessive ending, which is why you get yeri, not just yer.

Because Turkish normally puts modifiers before the thing they describe.

So:

• engelli = disabled
• park yeri = parking space

Together:

• engelli park yeri = disabled parking space

This is similar to English word order in this case, where disabled also comes before parking space.

Trafik işaretiyle means with a traffic sign or by means of a traffic sign.

It breaks down like this:

• trafik işareti = traffic sign
• -yle = with

So:

• trafik işaretiyle = with a traffic sign

This tells you the means or instrument used to indicate the parking space.

Both are possible.

• işareti ile
• işaretiyle

These mean the same thing: with its sign / with a sign

In modern Turkish, ile is often attached to the previous word and becomes:

• -la / -le
• or after vowels, often -yla / -yle

So:

• işareti ile → işaretiyle

The attached form is very common in normal writing.

Gösterilmiş means has been shown, has been indicated, or has been marked.

It comes from the verb göstermek, meaning to show.

Here is the structure:

• göster- = show
• -il- = passive
• -miş = reported/inferred past

So gösterilmiş literally means something like:

• it has been shown
• it appears to have been shown
• it is said to have been shown

In this sentence, a natural English translation is has been indicated/marked.

It is passive because the sentence focuses on the parking space, not on who did the action.

Compare:

• Birisi engelli park yerini trafik işaretiyle göstermiş.
  Someone indicated the disabled parking space with a traffic sign.

• Engelli park yeri trafik işaretiyle gösterilmiş.
  The disabled parking space has been indicated with a traffic sign.

Turkish uses the passive very often when the doer is unknown, unimportant, or obvious from context.

The -miş ending often gives a meaning like:

• reported information
• inferred information
• discovered result

So gösterilmiş is not just plain past. It can suggest:

• it has apparently been marked
• it turns out it was marked
• it is said to have been marked

In many contexts, English does not translate this nuance directly, so the simplest translation may just be has been indicated or was indicated.

Turkish does not have articles like English a/an and the.

So engelli park yeri can mean:

• a disabled parking space
• the disabled parking space

Which one is meant depends on context.

The same is true for trafik işaretiyle:

• with a traffic sign
• with the traffic sign

Context tells you which English article sounds best.

Not completely. Turkish word order is flexible, although some orders sound more neutral than others.

The given sentence:

• Engelli park yeri trafik işaretiyle gösterilmiş.

is a natural neutral order.

But Turkish could also move parts around for emphasis, for example:

• Trafik işaretiyle engelli park yeri gösterilmiş.

This still means roughly the same thing, but it may put more focus on trafik işaretiyle.

In Turkish, the verb often comes at the end, and the elements before it can be rearranged depending on emphasis.

Usually park yeri means a parking place, parking spot, or space to park.

If you want to say parking lot or car park, Turkish more often uses:

• otopark

So in this sentence, engelli park yeri most naturally means:

• disabled parking space
• disabled parking spot

not a whole parking lot.

Because in this sentence engelli park yeri is the subject of a passive sentence, not a direct object.

In an active sentence, you might get something like:

• Görevli engelli park yerini trafik işaretiyle göstermiş.
  The official indicated the disabled parking space with a traffic sign.

There, park yerini has the accusative ending because it is the direct object.

But in the passive version:

• Engelli park yeri trafik işaretiyle gösterilmiş.

the parking space becomes the grammatical subject, so no accusative is used.

In Turkish, göstermek literally means to show, but in practical English this sentence may sound better as:

• The disabled parking space is marked with a traffic sign.
• The disabled parking space has been indicated by a traffic sign.

So yes, depending on context, English marked may sound more natural than a literal shown.

That is very common when translating Turkish: the most literal verb is not always the most natural English choice.