Learn Hardcore Polish: Wieczorem siedzę z mamą na balkonie i pijemy herbatę. - I sit with my mom on the balcony in the evening and we drink tea.

Polish doesn’t usually say w wieczór.
The noun wieczór (evening) takes a special form wieczorem, which is historically the instrumental case but in practice works like an adverb of time: wieczorem = in the evening / this evening.

Polish uses similar forms for time expressions:

latem – in (the) summer
zimą – in (the) winter
nocą – at night

So Wieczorem siedzę… literally is “(I) sit in the evening…”, and that’s the natural way to say it. Using w wieczór would sound wrong or very odd.

Does this sentence mean a habitual action (“In the evenings I usually do this”) or something happening this evening?

It can mean either, depending on context.

By default, Wieczorem siedzę z mamą na balkonie i pijemy herbatę. is often understood as a habitual action:

In the evening I (usually) sit with my mom on the balcony and we drink tea.

But in the right context it can also refer to today’s evening:

e.g. answering Co dziś robisz? (What are you doing today?) – Wieczorem siedzę z mamą na balkonie i pijemy herbatę. → This evening I’m going to sit with my mom on the balcony and we’ll drink tea.

Polish present tense of imperfective verbs covers both “I do” and “I am doing / I will be doing (this evening)” depending on adverbs and context.

Why is it siedzę (“I sit”) but pijemy (“we drink”) in the same sentence? Is that allowed?

Yes, that’s perfectly normal. The subject can change inside a coordinated sentence.

siedzę – 1st person singular: I sit / I am sitting
pijemy – 1st person plural: we drink / we are drinking

So the structure is:

(Ja) wieczorem siedzę z mamą na balkonie – In the evening I sit with my mom on the balcony
(my) pijemy herbatę – and we drink tea

The second verb describes what both of you (you and your mom) do together after/while you’re sitting. Polish is fine with this kind of shift in subject as long as it’s clear from context.

If my mom is also sitting, shouldn’t it be siedzimy z mamą (“we sit with my mom”) instead of siedzę z mamą?

You can say Wieczorem siedzimy z mamą na balkonie i pijemy herbatę. That would mean:

In the evening we sit with my mom on the balcony and we drink tea.

The original siedzę z mamą puts the focus slightly more on “I” as the grammatical subject, even though in reality you probably both sit. Both versions are grammatical; it’s mostly a matter of style and emphasis.

Why is it z mamą and not z mama? What does the -ą ending mean?

The -ą ending shows the instrumental case singular of a feminine noun.

The base form is:

mama – mum / mom (nominative)

After the preposition z meaning with, Polish requires the instrumental case:

z kim? – with whom? → z mamą – with (my) mom

So:

mama (nominative) → mamą (instrumental)

Other similar examples:

z siostrą – with (my) sister
z koleżanką – with (my) (female) friend

Note that z can also take the genitive case when it means “from/out of” (e.g. z domu – from the house), but with the meaning “with”, it takes the instrumental: z mamą.

Why is it na balkonie and not na balkon?

The preposition na can take two different cases with different meanings:

na
- locative (static location) → on/at some place
- na balkonie – on the balcony (you are there)
na
- accusative (movement to a place) → onto/to some place
- na balkon – onto the balcony / to the balcony (you are going there)

In the sentence siedzę z mamą na balkonie, you’re already located on the balcony, so balkonie (locative) is correct. If you were describing movement, you’d use na balkon:

Wychodzimy na balkon. – We go out onto the balcony.

Why is there no word for “the” or “a” before balkonie or herbatę?

Polish has no articles like English a/an or the. Nouns usually appear without any article word, and specificity is understood from context.

So:

na balkonie can be on the balcony or on a balcony
pijemy herbatę can be we drink tea or we drink the tea

If you really need to be explicit, you use other means, e.g. demonstratives:

na tym balkonie – on this balcony
pijemy tę herbatę – we drink this (particular) tea

But in normal everyday speech, plain balkonie and herbatę are enough.

Why is it herbatę and not herbata?

Herbata is the base (nominative) form:

(ta) herbata – this tea (as a subject: Herbata jest gorąca.)

In pijemy herbatę, herbatę is the direct object of the verb drink, so it must be in the accusative case:

co pijemy? – what are we drinking? → herbatę

For many feminine nouns ending in -a, the accusative singular ending is -ę:

kawa → kawę – (we drink) coffee
zupa → zupę – (we eat) soup
herbata → herbatę – (we drink) tea

Why are ja (“I”) and my (“we”) not written? How do I know who is doing the action?

In Polish, subject pronouns are usually omitted because the verb ending shows the person and number clearly.

siedzę already tells you it’s I (1st person singular).
pijemy already tells you it’s we (1st person plural).

You use ja, my (and other subject pronouns) mainly for emphasis or contrast:

To ja siedzę z mamą. – It’s me who sits with mom.
My pijemy herbatę, a oni kawę. – We drink tea, and they drink coffee.

In neutral sentences like this one, leaving out the pronouns is more natural.

Do I need a comma before i (“and”) in …na balkonie i pijemy herbatę?

No comma is needed here in standard Polish.

Although siedzę and pijemy have different grammatical subjects (I vs. we), the sentence is seen as a compact sequence of actions with a shared context (wieczorem, z mamą, na balkonie). Polish punctuation rules allow (and prefer) no comma when the clauses share elements and are closely connected in meaning.

So:

Wieczorem siedzę z mamą na balkonie i pijemy herbatę. – correct, no comma
Adding a comma (…balkonie, i pijemy…) would look unusual or overly emphatic.

Is there a difference between Wieczorem and Wieczorami?

Yes:

wieczorem – in the evening / this evening / in the evenings (context decides; can be generic or one specific evening)
wieczorami – in the evenings, clearly plural and strongly habitual/repeated

So:

Wieczorem siedzę z mamą… – can mean This evening I’m sitting with my mom… or In the evening I (usually) sit with my mom…
Wieczorami siedzę z mamą… – clearly In the evenings I (regularly) sit with my mom…

If you want to stress a repeated habit, wieczorami is very clear.

Could I use perfective verbs here, like usiądę or wypijemy, and what would change?

You could, but the meaning would change.

In the original, both verbs are imperfective:

siedzieć → siedzę – I sit / I am sitting
pić → pijemy – we drink / we are drinking

Imperfective focuses on the process or repeated action.

If you use perfective:

Wieczorem usiądę z mamą na balkonie i wypijemy herbatę.

Now the meaning is more like a plan for a single, completed event:

In the evening I will sit down with my mom on the balcony and we will drink up (finish) the tea.

So:

Imperfective (siedzę, pijemy) – ongoing or habitual actions.
Perfective (usiądę, wypijemy) – single, completed actions, often with a future meaning in the present tense form.