Ο φωτισμός ασφαλείας λειτουργεί.

Ο is the definite article the.

In this sentence, ο is:

• masculine
• singular
• nominative

It matches φωτισμός, which is a masculine singular noun.

So:

• ο φωτισμός = the lighting

Because φωτισμός is a masculine noun.

Greek nouns have grammatical gender, and the article has to agree with the noun:

• ο for many masculine nouns
• η for many feminine nouns
• το for many neuter nouns

Since φωτισμός is masculine, you say ο φωτισμός.

Φωτισμός means lighting or illumination.

It is a noun, not a verb. So it refers to the lighting system or the state of being lit, depending on context.

In this sentence, it means the lighting, specifically the safety/emergency lighting.

Ασφαλείας is the genitive singular form of ασφάλεια (safety, security).

So:

• ασφάλεια = safety
• ασφαλείας = of safety / safety-related

That is why φωτισμός ασφαλείας literally means lighting of safety, which in natural English is safety lighting or emergency lighting.

This is a very common Greek structure:

• noun + genitive noun

For example:

• ζώνη ασφαλείας = seat belt, literally belt of safety
• έξοδος κινδύνου = emergency exit, literally exit of danger

Not word-for-word.

Literally, it is closer to:

• lighting of safety
• safety lighting

But in real usage, this often corresponds to English emergency lighting.

So the Greek uses safety language where English often uses emergency language. That is a normal difference between the two languages.

Λειτουργεί means works, functions, or is operating.

It is from the verb λειτουργώ = to function / to operate.

So:

• Ο φωτισμός ασφαλείας λειτουργεί. can mean:
• The emergency lighting works.
• The emergency lighting is operating.
• The safety lighting is functioning.

It is present tense, third person singular.

So:

• λειτουργώ = I function / operate
• λειτουργείς = you function
• λειτουργεί = he/she/it functions

Here the subject is ο φωτισμός ασφαλείας, which is singular, so the verb is also singular:

• λειτουργεί = works / is working

Greek present tense can often cover both English:

• works
• is working

The exact translation depends on context.

Because λειτουργεί is already a full verb meaning functions / works / operates.

In English, we might say:

• The lighting is working

But in Greek, λειτουργεί already expresses that idea by itself. You do not need είναι here.

So:

• λειτουργεί = works / is working not
• is functions

Yes, often you could say δουλεύει, especially in everyday speech.

• λειτουργεί = functions, operates
• δουλεύει = works

For machines, systems, devices, and equipment, δουλεύει is very common and conversational.

So:

• Ο φωτισμός ασφαλείας λειτουργεί. sounds a bit more formal or technical.
• Ο φωτισμός ασφαλείας δουλεύει. sounds more everyday.

Both can be correct depending on context.

A rough pronunciation guide is:

o fo-ti-SMOS as-fa-LI-as li-tour-GHI

A few notes:

• φ sounds like English f
• θ sounds like th in think
• γ before ε, ι often sounds like a soft sound similar to y in some contexts, but in λειτουργεί the sequence is a bit more complex; for learners, it is often enough at first to copy native audio
• the stressed syllables are marked by the accent:
  • φωτισμός
  • ασφαλείας
  • λειτουργεί

Stress matters a lot in Greek because it is part of the standard spelling and pronunciation.

In this sentence:

• φωτισμός
• ασφαλείας
• λειτουργεί

If you move the stress, the word may sound unnatural or wrong.

For English speakers, one useful habit is:

1. notice the accent mark
2. say that syllable more strongly

Yes. Greek word order is more flexible than English.

The neutral order here is:

• Ο φωτισμός ασφαλείας λειτουργεί.

But depending on emphasis, you might also hear:

• Λειτουργεί ο φωτισμός ασφαλείας.

That could sound like:

• The emergency lighting is working or
• The emergency lighting does work / is functioning

The basic meaning stays the same, but the emphasis may shift.

Sometimes yes, but it depends on context.

With the article:

• Ο φωτισμός ασφαλείας λειτουργεί. This sounds like a complete normal sentence: The emergency lighting works.

Without the article:

• Φωτισμός ασφαλείας λειτουργεί. This can sound more like:
• a headline
• a label
• a technical note
• sign-style language

In ordinary full-sentence Greek, keeping ο is the safest choice.

Because φωτισμός is grammatically a singular noun.

Even if the lighting system includes many individual lights, Greek treats ο φωτισμός as one singular system or category, just as English does in the lighting works.

So:

• singular subject: ο φωτισμός
• singular verb: λειτουργεί

It sounds natural and somewhat formal/technical, especially because of λειτουργεί.

You might see or hear it in:

• building systems
• safety checks
• maintenance reports
• equipment status messages

In very casual speech, someone might be more likely to say:

• Ο φωτισμός ασφαλείας δουλεύει.

But the original sentence is completely normal Greek.