Eve girer girmez değil, çıkarken ışıkları kapat.

Ev means house or home.

Here, eve uses the dative ending -e, which often shows movement toward a place. So eve girmek means to go into the house / enter the house.

Compare:

• eve = to the house / into the house
• evde = in the house
• evi = the house as a definite direct object

So in this sentence, eve is used because the action is entering into the house.

Girer girmez is a very common Turkish pattern meaning:

• as soon as (someone) enters
• the moment (someone) enters
• no sooner ... than ...

It is a fixed structure:

• girer = aorist form of girmek
• girmez = negative aorist form

Together, girer girmez functions like an adverbial time expression.

Other examples:

• Eve gelir gelmez beni ara.
  Call me as soon as you get home.
• Onu görür görmez tanıdım.
  I recognized him the moment I saw him.

So here, eve girer girmez means as soon as you enter the house.

Here değil does not negate the verb girmek itself. It is used for contrast.

The pattern is:

• X değil, Y = not X, but Y

So:

• Eve girer girmez değil, çıkarken...
  = Not as soon as you enter the house, but when leaving...

In other words, the speaker is correcting the timing:

• Don’t do it upon entering
• Do it while leaving

This is a very normal use of değil in Turkish.

Çıkarken means:

• while leaving
• when going out
• as you leave

It comes from çıkmak (to go out / leave) plus -ken, which often means while or when.

So:

• çıkarken = while going out / when leaving

This contrasts nicely with girer girmez:

• girer girmez = the instant you enter
• çıkarken = while you are going out / when you leave

Yes, both are time expressions, but they work differently.

• girer girmez = immediately upon entering
  • very punctual
  • emphasizes the exact moment right after the action
• çıkarken = while leaving / when leaving
  • broader
  • refers to the time during the act of going out

So the sentence contrasts:

• not immediately when entering
• but rather at the time of leaving

Because ışıkları is a definite direct object.

• ışıklar = lights in a general sense
• ışıkları = the lights

In Turkish, a specific/definite direct object usually takes the accusative ending.

So:

• Işıklar yanıyor.
  The lights are on.
• Işıkları kapat.
  Turn off the lights.

Here the speaker means specific lights already known from context, so ışıkları is the natural form.

Yes. Kapat is the informal singular imperative of kapatmak (to close / shut / turn off).

So ışıkları kapat means:

• turn off the lights

This is said to:

• one person informally, or
• as a general instruction

Related forms:

• kapatın = polite or plural turn off
• kapatma = don’t turn off

Turkish often leaves the subject unstated when it is already clear.

Here, the main verb is an imperative:

• kapat = turn off

That already tells you the subject is you.

So the sentence does not need sen. Adding sen would usually sound extra emphatic.

The understood subject of the time expressions is also the same person:

• you enter
• you leave
• you turn off the lights

Turkish usually puts:

1. time/context information first
2. the main verb at the end

So this sentence is structured roughly like:

• Eve girer girmez değil = not as soon as you enter the house
• çıkarken = when leaving
• ışıkları = the lights
• kapat = turn off

This ordering is very natural in Turkish, especially when the speaker is contrasting two time options.

Yes. Turkish has several ways to express the same basic idea.

For example:

• Işıkları eve girer girmez değil, çıkarken kapat.
• Eve girer girmez ışıkları kapatma; çıkarken kapat.

These are similar, but the original sentence is especially good at expressing the contrast:

• not then
• but then

So değil gives it a corrective feel, like the speaker is saying: Not at that time — at this time instead.

Yes, it is natural, especially in a contrastive or corrective context.

It sounds like someone is clarifying the proper moment for the action:

• Don’t do that right when you enter
• Do it when you leave

So it would fit situations like instructions, reminders, or correcting someone’s habit.