Ο γιατρός δουλεύει στην κλινική.

Ο is the masculine singular definite article, so it means the.

In this sentence, ο γιατρός means the doctor.

Greek articles change according to gender, number, and case, unlike English the, which always stays the same.

Greek often uses the definite article more regularly than English does.

So ο γιατρός is the normal way to say the doctor.
If you said just γιατρός, it would sound less complete in a normal sentence unless the context clearly called for it.

In other words, using the article here is the standard, natural Greek way.

Grammatically, ο γιατρός is masculine, so in this sentence it refers to a male doctor.

For a female doctor, Greek commonly says η γιατρός.
So the noun γιατρός itself can be used for both men and women, but the article shows the gender:

• ο γιατρός = the male doctor
• η γιατρός = the female doctor

Δουλεύει is the 3rd person singular present tense of δουλεύω = to work.

So δουλεύει means:

• he works
• she works
• it works

In this sentence, because the subject is ο γιατρός, it means he works.

Some useful present-tense forms are:

• δουλεύω = I work
• δουλεύεις = you work
• δουλεύει = he/she/it works
• δουλεύουμε = we work
• δουλεύετε = you all / you formal work
• δουλεύουν = they work

Greek usually does not need a subject pronoun if the verb already shows the person and number.

So instead of saying something like He works, Greek can simply say:

• Ο γιατρός δουλεύει.

The verb ending -ει already tells you it is 3rd person singular, and the noun ο γιατρός tells you who the subject is.

Greek pronouns such as αυτός (he) are usually added only for emphasis, contrast, or clarity.

Στην is the common contracted form of σε την.

• σε = in / at / to
• την = the (feminine accusative singular)

So:

• σε την κλινική → στην κλινική

This contraction is very common in everyday Greek.

Similarly:

• σε το → στο
• σε τον → στον
• σε τους → στους
• σε τις → στις

After the preposition σε (and therefore after στην), Greek normally uses the accusative case.

So στην κλινική means in/at the clinic, and κλινική is in the accusative singular.

For this noun, the accusative form looks the same as the nominative:

• η κλινική = the clinic (nominative)
• την κλινική = the clinic (accusative)

That is why you see στην κλινική.

It can mean any of those, depending on context.

The basic preposition is σε, which often covers meanings that English splits into different prepositions:

• in
• at
• to

So στην κλινική could literally match in the clinic, at the clinic, or sometimes to the clinic, depending on the sentence.

In Ο γιατρός δουλεύει στην κλινική, the natural meaning is at/in the clinic.

Yes. Both can mean works.

• δουλεύει is very common and everyday
• εργάζεται is a bit more formal or neutral in style

So both of these are possible:

• Ο γιατρός δουλεύει στην κλινική.
• Ο γιατρός εργάζεται στην κλινική.

They are very close in meaning here.

One thing to know: δουλεύω can also mean function/work for machines, as in The computer isn’t working.

A rough pronunciation guide is:

o ya-TROS thoo-LEV-ee stin klee-nee-KEE

A few useful notes:

• για sounds roughly like ya
• τρ in γιατρός is a consonant cluster, like tr
• ου sounds like oo in food
• ευ in δουλεύει is pronounced ev or ef depending on the next sound; here it is ev
• η, ι, and υ in Modern Greek all sound like ee
• The written accent shows which syllable is stressed:
  • γιατρός
  • δουλεύει
  • κλινική

The accent mark shows which syllable gets the stress.

So:

• γιατρός
• δουλεύει
• κλινική

Stress matters in Greek pronunciation, and it is written, so learners should pay attention to it from the beginning.

If you ignore the accent, your Greek may still be understood, but it will sound less natural and can sometimes cause confusion.

Greek word order is more flexible than English word order.

The neutral, straightforward order here is:

• Ο γιατρός δουλεύει στην κλινική.

But Greek can sometimes move things around for emphasis, for example:

• Στην κλινική δουλεύει ο γιατρός.

That could sound like It’s at the clinic that the doctor works or put more focus on the location.

So the basic sentence order is common and natural, but Greek does allow more variation than English.

It can often mean either one, depending on context.

Greek present tense is used both for:

• something happening now
• something that is generally true or habitual

So Ο γιατρός δουλεύει στην κλινική can mean:

• The doctor is working at the clinic (right now, depending on context)
• The doctor works at the clinic (in general)

Usually the surrounding context makes it clear.

Because in Greek every noun has a grammatical gender: masculine, feminine, or neuter.

Κλινική is a feminine noun, so it takes feminine articles:

• η κλινική = the clinic
• την κλινική = the clinic (accusative)
• στην κλινική = in/at the clinic

This is a feature of Greek grammar and does not necessarily mean anything special beyond the noun’s grammatical class.