Είδαμε ένα φίδι στον κήπο.

Because the verb ending already tells you the subject.

• Είδαμε = we saw
• The ending -αμε marks 1st person plural (we)

So Greek often leaves out subject pronouns when they are not needed.
You could say Εμείς είδαμε ένα φίδι στον κήπο, but εμείς would add emphasis, like we saw it.

Είδαμε means we saw.

It is the simple past in Greek, usually called the aorist. In this sentence, it refers to a completed action in the past: you saw the snake at some point.

A useful thing to know is that this verb comes from βλέπω (I see), but the past stem changes:

• βλέπω = I see
• είδα = I saw
• είδαμε = we saw

So this is one of those common verbs whose past form is not built in a fully regular way.

Because φίδι is a neuter singular noun, and the article/adjective must match it.

Greek indefinite article forms are:

• ένας for masculine
• μία / μια for feminine
• ένα for neuter

Since φίδι (snake) is neuter, you use ένα:

• ένα φίδι = a snake

Φίδι is neuter.

One clue is the ending -ι, which is very often neuter in Modern Greek, though not always. Its article also shows the gender:

• το φίδι = the snake
• ένα φίδι = a snake

So if you learn nouns together with their article, it becomes easier to remember gender:

• το φίδι, not just φίδι

Because κήπος is a masculine noun, and after σε you use the accusative form with the matching article.

• ο κήπος = the garden (nominative)
• τον κήπο = the garden (accusative)

Then σε + τον contracts to στον:

• σε τον κήπο → στον κήπο

So:

• στον κήπο = in the garden / into the garden / at the garden, depending on context

If the noun were neuter, you would usually get στο:

• στο σπίτι = in the house

Στον is a contraction of:

• σε = in / to / at / on
• τον = the (masculine accusative singular)

So:

• σε τον → στον

This kind of contraction is very common in Modern Greek:

• σε το → στο
• σε την → στη(ν)
• σε τους → στους

In Modern Greek, σε + accusative is used for many meanings that English expresses with different prepositions, such as:

• in
• to
• at
• sometimes on

So στον κήπο can mean in the garden here because the context is location.

This is very normal in Greek. English often uses more different prepositions than Greek does.

Because after σε (and with τον), the noun is in the accusative case, not the nominative.

Compare:

• ο κήπος = the garden (subject form / nominative)
• τον κήπο = the garden (object/prepositional form / accusative)

So the sentence uses:

• στον κήπο = σε + τον κήπο

This is a very common pattern in Greek: the form of the noun changes depending on its grammatical role.

Because different noun types behave differently.

• φίδι is neuter, and in the singular its nominative and accusative forms are the same:

  • το φίδι
  • ένα φίδι

• κήπος is masculine, and masculine nouns often have a different accusative singular:

  • ο κήπος
  • τον κήπο

So even though both nouns are objects or part of a prepositional phrase, their endings do not have to change in the same way.

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

The neutral order here is:

• Είδαμε ένα φίδι στον κήπο.

But you could also say:

• Στον κήπο είδαμε ένα φίδι.
  This puts more focus on in the garden.

• Ένα φίδι είδαμε στον κήπο.
  This can emphasize a snake.

The original sentence is a very natural, straightforward way to say it.

A simple pronunciation guide would be:

• Είδαμε ≈ EE-tha-me
• ένα ≈ EH-na
• φίδι ≈ FEE-thee
• στον ≈ ston
• κήπο ≈ KEE-po

So the whole sentence is roughly:

EE-tha-me EH-na FEE-thee ston KEE-po

A few notes:

• δ sounds like th in this
• θ sounds like th in think
• The accent marks show which syllable gets the stress:
  • Είδαμε
  • ένα
  • φίδι
  • κήπο

It can mean both a/an and one.

In this sentence, ένα φίδι most naturally means a snake.

If you wanted to strongly emphasize the number, one snake, the context or intonation would usually make that clear. Greek uses the same word, just as English sometimes uses one for emphasis.

Sometimes Greek can omit the indefinite article, but in this sentence ένα φίδι is the most natural and standard way to say a snake.

• Είδαμε ένα φίδι στον κήπο. = the normal, clear version
• Είδαμε φίδι στον κήπο. can sound more general or stylistically different, depending on context

For a learner, it is best to use ένα φίδι here.

In Modern Greek, accent marks show which syllable is stressed.

For example:

• Είδαμε → stress on Εί-
• φίδι → stress on φί-
• κήπο → stress on κή-

This matters for correct pronunciation, and it is part of normal spelling in Greek. So when you learn vocabulary, it is important to learn the accent too.