Learn Hardcore Croatian: Večeras sjedimo bliže prozoru. - Tonight we are sitting closer to the window.

sjedimo = “we sit / we are sitting” (1st person plural is clear from the ending -imo)
So Mi večeras sjedimo bliže prozoru is grammatically correct, but it sounds unnecessarily heavy unless you want to emphasize we (for example, contrasting with someone else).

What tense is sjedimo here? Does it mean “we sit” or “we are sitting”?

Croatian has only one present tense, and it covers both:

“we sit” (general/habitual)
“we are sitting” (right now / in this situation)

In this sentence, context (and večeras) makes it mean something like English “Tonight we’re sitting closer to the window.”

So sjedimo is present tense, imperfective aspect, and you translate it as either “we sit” or “we are sitting” depending on context.

How can the present tense refer to the future here? We say “tonight we are sitting…”, but it’s about a plan.

Croatian, like English, can use the present tense for scheduled or planned future actions when there is a time expression:

Večeras sjedimo bliže prozoru.
= “Tonight we’re sitting closer to the window.” (plan / arrangement)

You could also use a future form:

Večeras ćemo sjediti bliže prozoru.
= “Tonight we will sit / will be sitting closer to the window.”

Both are correct. The version with simple present (as in your sentence) sounds natural and conversational.

What exactly does večeras mean? How is it different from večer or noćas?

večeras = “this evening / tonight” as a time adverb (when?)
večer = “evening” as a noun (e.g. dobra večer – “good evening”)
noćas = “tonight / during the night” (more focused on night-time, often later than večeras)

In your sentence, večeras is a time adverb meaning “this evening / tonight”.

Can večeras go somewhere else in the sentence? For example: Sjedimo večeras bliže prozoru?

Yes. Word order is flexible:

Večeras sjedimo bliže prozoru. (neutral, common)
Sjedimo večeras bliže prozoru. (slight emphasis on the act of sitting or on the contrast with other times)
Sjedimo bliže prozoru večeras. (emphasis can fall a bit more on tonight at the end)

All are grammatical; the difference is mainly in rhythm and emphasis, not in basic meaning.

What is sjedimo grammatically? How is it formed?

sjedimo is:

verb: sjediti (to sit)
person/number: 1st person plural
tense: present
aspect: imperfective

Present conjugation of sjediti (short form):

ja sjedim – I sit / am sitting
ti sjediš – you sit / are sitting
on/ona/ono sjedi – he/she/it sits / is sitting
mi sjedimo – we sit / are sitting
vi sjedite – you (pl./formal) sit / are sitting
oni/one/ona sjede – they sit / are sitting

What does bliže mean, and what form is it?

bliže is the comparative form of blizu (“near, close”).
So:

blizu = near / close
bliže = nearer / closer

In this sentence it’s an adverb: bliže prozoru = “closer to the window.”

Why is it prozoru and not prozor or prozora?

prozoru is the dative singular form of prozor (“window”).

Declension of prozor (singular, masculine):

Nominative: prozor
Genitive: prozora
Dative: prozoru
Accusative: prozor
Locative: prozoru
Instrumental: prozorom

After bliže (in this “closer to X” sense), Croatian often uses the dative case:

bliže prozoru – closer (to) the window
So prozoru is required here by the grammar pattern bliže + dative.

Could I say bliže do prozora instead of bliže prozoru?

No; that sounds unnatural in Croatian.

Correct and natural: bliže prozoru (dative)
Using do would normally require the genitive (do prozora), but bliže do prozora is not idiomatic. Stick with bliže prozoru for “closer to the window.”

What’s the difference between bliže prozoru, kod prozora, and pored prozora?

bliže prozoru – “closer to the window” (focus on compared to some other place; comparative idea)
kod prozora – “by / at the window” (location, near it)
pored prozora – “next to the window” (immediately beside it)

Your sentence stresses the comparative idea (we’re sitting closer than before or closer than somewhere else), so bliže prozoru fits best.

Could I say Večeras ćemo sjediti bliže prozoru? How is that different?

Yes, you can.

Večeras sjedimo bliže prozoru.
– present tense with a future meaning (very natural, conversational)
Večeras ćemo sjediti bliže prozoru.
– explicit future tense (ćemo sjediti = “we will sit”)

Both mean essentially the same. The future form can sound a bit more explicit or formal; the simple present is very common in everyday speech for planned events.

What’s the difference between sjediti and sjesti?

sjediti – “to sit” (state, being in a sitting position; imperfective)
sjesti – “to sit down” (single action of moving into a sitting position; perfective)

So:

Večeras sjedimo bliže prozoru.
– We are (going to be) sitting closer to the window (focus on where we sit).
Večeras ćemo sjesti bliže prozoru.
– We will sit down closer to the window (focus on the act of sitting down there).

In your sentence, sjedimo focuses on the location/state of sitting, not on the moment of sitting down.