Σήμερα περνάω από το φαρμακείο πριν πάω σπίτι.

Today I’m stopping by the pharmacy before I go home.

Breakdown of Σήμερα περνάω από το φαρμακείο πριν πάω σπίτι.

• πάω: to go
• το σπίτι: the home
• σήμερα: today
• πριν: before
• το φαρμακείο: the pharmacy
• περνάω από: to stop by

Questions & Answers about Σήμερα περνάω από το φαρμακείο πριν πάω σπίτι.

What does περνάω από το φαρμακείο mean exactly—am I just passing by, or actually going in?

Περνάω από + place literally means I pass by / I go via that place. In real life it often implies stopping by briefly (possibly going in), but it doesn’t guarantee it.

• If you want to clearly say you’re going to the pharmacy (as a destination), you’d more typically use πάω στο φαρμακείο or πηγαίνω στο φαρμακείο.
• περνάω από το φαρμακείο feels like: it’s on the way, or it’s a quick errand en route.

Why is περνάω in the present tense if it’s about “today” and might be in the future?

Greek often uses the present tense for something that is planned/expected (especially with a time word like Σήμερα). It can sound like English I’m going by the pharmacy today.
If you want to be explicit about the future, you can also say Σήμερα θα περάσω από το φαρμακείο... (future with θα).

Why do we use από here, and what grammatical case is το φαρμακείο in?

With verbs like περνάω (pass), Greek commonly uses από to express passing by/through/via a place.
Most prepositions in Modern Greek (including από) take the accusative. So από το φαρμακείο is accusative.
With neuter nouns, nominative and accusative often look the same (το φαρμακείο), but you’ll see the difference with masculine/feminine, e.g. από τον γιατρό, από τη δουλειά.

Why is it πριν πάω σπίτι and not πριν να πάω σπίτι?

Both are possible:

• πριν (να) πάω σπίτι
  Greek often omits να after πριν, especially in everyday speech. Keeping να can sound a bit more explicit or careful, but neither is “wrong” in normal Modern Greek.

Is πάω here indicative or subjunctive? It looks like “I go”.

After πριν, Greek uses the subjunctive (even when να is omitted).
For the verb πηγαίνω/πάω, the subjunctive present form for “I” is (να) πάω, which looks identical to the indicative πάω. The context (πριν) is what signals that it functions as subjunctive here.

Why is it πάω σπίτι without στο? Shouldn’t it be πάω στο σπίτι?

Both exist, with a meaning difference:

• πάω σπίτι = I go home (home as a general destination; very common)
• πάω στο σπίτι = I go to the house/home (more specific, often “to my/that house”; can sound more literal or emphasized)

Can the word order change, or is Σήμερα forced to be first?

Word order is flexible. Σήμερα is often placed first for emphasis/clarity, but you can also say, for example:

• Περνάω σήμερα από το φαρμακείο πριν πάω σπίτι.
• Πριν πάω σπίτι, περνάω από το φαρμακείο σήμερα. (more “framed,” often with a pause)
  Changing word order mostly changes focus, not core meaning.

What’s the deal with the stress marks—how do they help me pronounce this sentence?

Stress marks show which syllable is stressed (important in Greek). For example:

• Σήμερα: stress on Σή-
• περνάω: stress on -νά-
• φαρμακείο: stress on -εί-
• πριν: one syllable
• πάω: stress on πά-
• σπίτι: stress on σπί-
  If you move or miss the stress, you can sound unnatural, and sometimes you can even change the word.

Could I replace περνάω από το φαρμακείο with πηγαίνω στο φαρμακείο? What changes?

Yes, but the nuance changes:

• πηγαίνω στο φαρμακείο = the pharmacy is the destination (clear intention to go there)
• περνάω από το φαρμακείο = the pharmacy is along the route / a quick stop on the way somewhere else
  So your original sentence strongly supports the idea of “on the way home, I’m going by the pharmacy.”