Δουλεύει στο καζίνο.

Greek often leaves out subject pronouns because the verb ending already shows the person and number.

Here, δουλεύει means he/she/it works or is working.
So Δουλεύει στο καζίνο can mean:

• He works at the casino
• She works at the casino
• in some contexts, even It works at the casino, though that is much less likely

If you want to make the subject explicit, you can add a pronoun or noun:

• Αυτός δουλεύει στο καζίνο. = He works at the casino.
• Αυτή δουλεύει στο καζίνο. = She works at the casino.

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

So δουλεύει can mean:

• he works
• she works
• he is working
• she is working

Greek present tense often covers both the simple present and the present continuous, depending on context.

It is pronounced roughly thoo-LEV-ee.

A few helpful points:

• δ in Modern Greek sounds like the th in this, not like English d
• ου sounds like oo in food
• the stress is on -λεύ-

So a rough English-style pronunciation is:

thoo-LEV-ee

στο means in the, at the, or to the, depending on context.

It is a contraction of:

• σε = in / at / to
• το = the for a neuter singular noun

So:

• σε το → στο

In this sentence:

• στο καζίνο = at the casino

This contraction is very common in Greek.

Because Greek often uses the definite article where English may or may not use it.

• στο καζίνο = at the casino

Using σε καζίνο without the article is possible in some contexts, but it is less neutral here.
In a simple sentence like this, στο καζίνο sounds natural and standard.

In Greek, every noun has grammatical gender: masculine, feminine, or neuter.

καζίνο is a neuter noun, so it takes the neuter article:

• το καζίνο = the casino

That is why after σε + το, you get στο καζίνο.

In this sentence, καζίνο stays the same form.

After σε (or στο), Greek normally uses the accusative case.
But many neuter nouns, especially ones like καζίνο, look the same in the nominative and accusative.

So:

• nominative: το καζίνο
• accusative: το καζίνο

The article and preposition show the grammar, even though the noun itself does not change.

Yes.

The Greek present tense often covers both meanings:

• habitual: He works at the casino
• right now / currently: He is working at the casino

Context tells you which meaning is intended.

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

The most neutral version is:

• Δουλεύει στο καζίνο.

But you could also say:

• Στο καζίνο δουλεύει.

That version puts more emphasis on at the casino—for example, if you are contrasting it with another place.

The dictionary form is δουλεύω = to work.

Present tense:

• δουλεύω = I work / am working
• δουλεύεις = you work / are working (singular, informal)
• δουλεύει = he/she/it works / is working
• δουλεύουμε or δουλεύομε = we work / are working
• δουλεύετε = you work / are working (plural or polite singular)
• δουλεύουν or δουλεύουνε = they work / are working

So δουλεύει is the he/she/it form.

Usually it means works in the sense of having a job or doing work, but it can also mean functions or operates, depending on context.

For example:

• Δουλεύει στο καζίνο. = He/She works at the casino.
• Το μηχάνημα δεν δουλεύει. = The machine doesn’t work.

So the same verb can refer to a person working or to something functioning.

The stressed syllables are:

• Δουλεύει
• στο
• καζίνο

So roughly:

thoo-LEV-ee sto ka-ZEE-no

The written accent mark shows where the stress falls:

• δουλεύει
• καζίνο

Yes. Εργάζεται στο καζίνο also means He/She works at the casino.

The difference is style:

• δουλεύει = more common in everyday speech
• εργάζεται = a bit more formal or neutral

Both are correct, but δουλεύει στο καζίνο is very natural in conversation.