Eğer perdeler koyu renkliyse, sabah ışığı daha geç içeri girer.

Eğer means if.

In this sentence, it introduces the condition: If the curtains are dark-colored...

It is often optional in Turkish when the conditional ending already makes the meaning clear. So you could also say:

Perdeler koyu renkliyse, sabah ışığı daha geç içeri girer.

That still means the same thing. Using eğer just makes the if relationship more explicit.

Perde means curtain, and perdeler means curtains.

Turkish uses the plural suffix -ler / -lar here because the sentence is talking about curtains in general, or the curtains in a room. English also uses the plural naturally: If the curtains are dark-colored...

The suffix is -ler here because of vowel harmony: perde has front vowels, so the plural becomes perdeler.

Koyu renkliyse means if it/they are dark-colored.

It can be broken down like this:

• koyu = dark
• renkli = colored / having color
• ise = if it is / if they are

When ise attaches to the previous word, it often becomes -yse / -ysa after a vowel. So:

• renkli + ise → renkliyse

So perdeler koyu renkliyse literally means something like:

if the curtains are of a dark color

This happens because renkli ends in a vowel.

When ise is attached to a word ending in a vowel, Turkish usually inserts a buffer y:

• güzel + ise → güzelse
• hasta + ise → hastaysa
• renkli + ise → renkliyse

So -yse here is just the attached form of ise.

Yes. Koyu renkli works together as an adjective phrase meaning dark-colored.

• koyu = dark
• renkli = colored

So together they describe the curtains.

You could think of it as similar to English expressions like light-colored, red-colored, or dark-colored.

Sabah ışığı is a very common Turkish noun phrase meaning morning light.

This is a type of noun compound:

• sabah = morning
• ışık = light
• ışığı = light + compound ending

In Turkish, this structure often corresponds to English noun+noun combinations:

• yaz tatili = summer vacation
• mutfak masası = kitchen table
• sabah ışığı = morning light

You might also see sabahın ışığı, but that sounds more like the light of the morning, which is more specific or poetic. In ordinary usage, sabah ışığı is the more natural choice here.

This is because of the third-person possessive suffix used in Turkish noun compounds.

The base word is:

• ışık = light

In a compound like sabah ışığı (morning light), the second noun usually takes this ending:

• ışık → ışığı

The final k changes to ğ because it is between vowels after the suffix is added, which is a common sound change in Turkish.

So:

• sabah ışığı = morning light

This does not mean someone literally possesses the light; it is just how this compound structure works in Turkish.

Daha geç means later or more literally more late.

• geç = late
• daha = more

Turkish often forms comparatives with daha:

• daha büyük = bigger
• daha güzel = more beautiful
• daha geç = later

So here, sabah ışığı daha geç içeri girer means the morning light comes in later.

Literally, içeri girer means enters inside or goes in.

• içeri = inside / inward
• girer = enters / goes in

In natural English, we would usually say:

the morning light comes in later

Turkish often uses girmek with içeri for entering a space:

• Odaya içeri girdi. = He/She went inside the room.
• Işık içeri giriyor. = The light is coming in.

So the phrase is very natural in Turkish.

Girer is the aorist form, which is often used for general truths, habits, or things that typically happen.

Here the sentence is making a general statement:

If the curtains are dark-colored, the morning light comes in later.

That is why girer is a good choice.

By contrast:

• giriyor = is entering / is coming in

That would sound more like something happening right now in a specific situation.

So:

• girer = general fact or usual result
• giriyor = ongoing action right now

Putting the if clause first is very common in Turkish, just as in English:

Eğer perdeler koyu renkliyse, sabah ışığı daha geç içeri girer.

It can make the sentence easier to follow: first the condition, then the result.

You can also change the order:

Sabah ışığı, eğer perdeler koyu renkliyse, daha geç içeri girer.

But the original order is more straightforward and natural for a learner.

Not naturally in this sentence.

Koyu by itself means dark, but koyu renkli specifically means dark-colored. Since the sentence is describing the color of the curtains, koyu renkliyse is clearer and more idiomatic.

If the context already made it obvious that you were talking about color, a shorter version might sometimes work in conversation, but koyu renkliyse is the safer and more natural phrase.

Yes, they can definitely appear together, and this is normal Turkish.

Both help mark the conditional idea:

• eğer = if
• -yse / -ysa = if it is / if they are

Using both can feel a bit more explicit, similar to saying if clearly at the start of an English sentence even though the rest of the structure already shows the condition.

So this is completely natural:

Eğer perdeler koyu renkliyse, sabah ışığı daha geç içeri girer.

It is not wrong or strange. It is just a clearly marked conditional sentence.