Η μικροσυσκευή λειτουργεί.

Η means the.

It is the feminine singular definite article in the nominative case, because μικροσυσκευή is a feminine singular noun and it is the subject of the sentence.

So:

• η = the for feminine singular nouns
• μικροσυσκευή = a feminine singular noun
• Η μικροσυσκευή = the microdevice

In Modern Greek, Η is pronounced ee, not like the English letter name H.

Because Greek nouns have grammatical gender, and μικροσυσκευή happens to be feminine.

This does not mean the object is biologically female. In Greek, inanimate things also have grammatical gender.

A useful clue is the ending:

• nouns ending in -ή are often feminine

So learners will often recognize μικροσυσκευή as feminine partly because of its ending.

It is in the nominative case.

You can tell because it is the subject of the sentence: it is the thing that functions / works.

In Η μικροσυσκευή λειτουργεί, the structure is:

• Η μικροσυσκευή = the subject
• λειτουργεί = the verb

That is why the article is Η and not another form such as τη(ν).

A rough pronunciation guide is:

ee mee-kro-see-skeh-VEE lee-toor-YEE

More approximately in syllables:

• Η → ee
• μι-κρο-συ-σκευ-ή → mee-kro-see-skeh-VEE
• λει-τουρ-γεί → lee-toor-YEE

A few helpful points:

• η, ι, υ, ει, οι often sound like ee in Modern Greek
• the stress in μικροσυσκευή is on the last syllable
• the stress in λειτουργεί is also on the last syllable

The accent marks show which syllable is stressed.

So:

• μικροσυσκευή → stress on -ή
• λειτουργεί → stress on -εί

Stress matters in Greek pronunciation, so these marks are important.

In this sentence, the accents tell you to say:

• μικροσυσκευή
• λειτουργεί

λειτουργεί is the 3rd person singular present tense form of the verb λειτουργώ, which means to function, to operate, or to work.

Why 3rd person singular?

Because the subject is one thing:

• Η μικροσυσκευή = the microdevice = it

So Greek uses the equivalent of it works / it functions:

• λειτουργεί = it works / it is functioning

No. Depending on context, λειτουργεί can mean:

• works
• functions
• operates
• is working
• is functioning

For a device, all of these can be possible translations depending on the situation.

So Η μικροσυσκευή λειτουργεί could be understood as:

• The microdevice works
• The microdevice is working
• The microdevice functions

Because Greek often does not need an explicit subject pronoun when the verb ending already shows the person and number.

In English, you usually say:

• It works

In Greek, the verb form λειτουργεί already tells you it is 3rd person singular, so a separate it is usually unnecessary.

The noun itself is already present anyway:

• Η μικροσυσκευή λειτουργεί = literally The microdevice works

Greek can use subject pronouns, but it often leaves them out unless there is emphasis or contrast.

Yes. Greek word order is more flexible than English word order.

The most neutral order here is:

• Η μικροσυσκευή λειτουργεί.

But you could also say:

• Λειτουργεί η μικροσυσκευή.

That still means basically the same thing, but it may sound more marked or context-dependent, for example if you are emphasizing the fact that it is functioning.

English usually has to keep a more fixed order, but Greek can move things around more easily because endings and articles help show each word's role.

Usually, in normal everyday Greek, no if you mean the microdevice.

Greek uses the definite article more often than English in many situations. So the natural sentence is:

• Η μικροσυσκευή λειτουργεί.

If you remove the article, it can sound unnatural in ordinary speech, or it may sound like:

• a headline
• a label
• a very context-specific phrase

If you want a microdevice works / is working, you would normally use:

• Μια μικροσυσκευή λειτουργεί.

So:

• Η μικροσυσκευή = the microdevice
• Μια μικροσυσκευή = a microdevice

You would say:

Η μικροσυσκευή δεν λειτουργεί.

Here:

• δεν = not
• λειτουργεί = works / is functioning

So the pattern is very simple:

• Η μικροσυσκευή λειτουργεί. = The microdevice works.
• Η μικροσυσκευή δεν λειτουργεί. = The microdevice does not work.

The plural would be:

Οι μικροσυσκευές λειτουργούν.

That means The microdevices work / are functioning.

Changes:

• Η → Οι for the plural article
• μικροσυσκευή → μικροσυσκευές for the plural noun
• λειτουργεί → λειτουργούν for the plural verb

So Greek changes both the noun phrase and the verb to match the plural subject.