Learn Hardcore Greek: Στέλνω ένα γράμμα στη γιαγιά μου και πηγαίνω στο ταχυδρομείο μετά τη δουλειά. - I send a letter to my grandmother and go to the post office after work.

So εγώ (I) is understood and normally omitted unless you want to emphasize I (e.g. Εγώ στέλνω… = I (as opposed to someone else) am sending…).

Why do we say ένα γράμμα? What does ένα do here?

Ένα is the neuter singular form of the indefinite article, like English a / an.

ένα γράμμα = a letter (not a specific one that we’ve already talked about)
γράμμα is neuter, so the article must also be neuter: ένα (not ένας or μία).

So the phrase is literally I send a letter…, not I send the letter… (which would be στέλνω το γράμμα).

Why is it γράμμα and not something like γράμματα or γράμματος? What case and number is this?

Γράμμα here is:

singular (one letter, not many)
accusative case, because it is the direct object of the verb στέλνω

For comparison:

(ονομαστική) το γράμμα – the letter (subject)
(αιτιατική) το γράμμα – the letter (object; same form in this noun)
(πληθυντικός) τα γράμματα – the letters

So ένα γράμμα is one letter as the thing being sent.

What exactly is στη in στη γιαγιά μου? Is it one word or two?

Στη is a contracted form of σε + τη(ν):

σε = to / in / at
τη(ν) = the (feminine singular accusative)

When they combine, they normally become one word:

σε + τη(ν) γιαγιά → στη(ν) γιαγιά

So στη γιαγιά μου literally means to the grandmother of me = to my grandmother.

Sometimes I see στην and sometimes στη. Why is it στη γιαγιά μου here and not στην γιαγιά μου?

Historically, στην is σε + την, and the final ν is often kept:

before vowels (e.g. στην Ελλάδα)
before certain consonants (like κ, π, τ, ξ, ψ, μπ, ντ, γκ, τσ, τζ)

With γιαγιά (starting with γ), both spellings στη γιαγιά and στην γιαγιά occur in real life. Modern informal writing often drops the ν except where it’s clearly needed for pronunciation, so στη γιαγιά is very common and perfectly understandable. In more careful or traditional writing you might see στην γιαγιά.

Why does μου (my) come after γιαγιά in στη γιαγιά μου, instead of before like in English?

In Greek, possessive pronouns normally come after the noun and article:

η γιαγιά μου = my grandmother (literally the grandmother my)
το βιβλίο σου = your book

So στη γιαγιά μου = to my grandmother, with:

στη = to the
γιαγιά = grandmother
μου = my

Putting μου before the noun (μου γιαγιά) is not standard in this meaning.

Why do we need στη before γιαγιά? Why can’t we just say στέλνω ένα γράμμα γιαγιά μου?

Greek normally uses σε (here contracted to στη) to mark the indirect object (the person you send something to):

Στέλνω ένα γράμμα στη γιαγιά μου. = I send a letter *to my grandmother.*

Without σε / στη, γιαγιά μου would just be hanging there and the sentence would sound wrong or at least incomplete. Compare:

Δίνω το βιβλίο στον φίλο μου. = I give the book to my friend.

So στη γιαγιά μου is required to express “to my grandmother”.

Why is it στο ταχυδρομείο for “to the post office” if σε usually means “in/at”?

Greek σε (here στο = σε + το) is very flexible. It can mean:

in/at: Είμαι στο ταχυδρομείο. = I am at the post office.
to (with verbs of motion): Πηγαίνω στο ταχυδρομείο. = I am going to the post office.

The direction (to vs. in/at) comes mainly from the verb, not from changing the preposition. With verbs like πηγαίνω, έρχομαι, τρέχω etc., σε is normally understood as “to”.

Why is there το in στο ταχυδρομείο, but we don’t say σε ένα ταχυδρομείο here?

Στο is σε + το, so στο ταχυδρομείο literally means to the post office.

We use the definite article when we mean a specific or “the usual / known” post office, often the one in your area or the one both speakers have in mind.

Πηγαίνω στο ταχυδρομείο. = I’m going to the post office (the known one).
Πηγαίνω σε ένα ταχυδρομείο. = I’m going to a post office (some post office, not a specific one already known).

In everyday speech, for regular places (the bank, the supermarket, the post office), Greek tends to prefer the definite article.

What case is ταχυδρομείο in στο ταχυδρομείο, and why that case?

Ταχυδρομείο here is neuter singular accusative.

With σε expressing location or direction, the noun that follows is normally in the accusative:

στο ταχυδρομείο (accusative)
στη δουλειά (accusative)
στο σπίτι (accusative)

So πηγαίνω στο ταχυδρομείο uses accusative because στο actually contains the preposition plus the article in the accusative.

Why is it μετά τη δουλειά and not just μετά δουλειά? What does the article τη do here?

In this sentence, δουλειά is treated as a specific, known time period: after *the work (day/shift)*. So:

μετά τη δουλειά = after work (after my/the workday)

Greek normally uses the article with nouns like this, where English often drops it:

το βράδυ = (in) the evening
το πρωί = (in) the morning

You could also hear μετά από τη δουλειά; μετά and μετά από are both used, with από making the starting point a bit more explicit. In all these, δουλειά is again in the accusative after the preposition.

The actions happen “after work”, so why are the verbs Στέλνω and πηγαίνω in the present tense? Shouldn’t it be future?

Modern Greek often uses the present tense to talk about near-future plans or scheduled actions, especially in informal speech, just like English can:

Greek: Αύριο πηγαίνω στο ταχυδρομείο.
English: Tomorrow I’m going to the post office. (present progressive for the future)

In your sentence, μετά τη δουλειά gives the future time, and the present tense is understood as a planned/expected action. If you want to emphasize the future more explicitly, you can use θα:

Θα στείλω ένα γράμμα… και θα πάω στο ταχυδρομείο… = I will send a letter… and I will go…

In English we say “I am sending / I am going”. How does Greek express that continuous idea if it just says Στέλνω and πηγαίνω?

Greek present tense usually covers both:

simple present: I send, I go
present continuous: I am sending, I am going

Context decides which English form is better. So Στέλνω ένα γράμμα can mean either:

I send a letter (regularly / in general), or
I am sending a letter (now / as part of a plan)

If you need to be very precise about ongoing action right now, you often add adverbs or context (e.g. Τώρα στέλνω ένα γράμμα. = I’m sending a letter now.).