Dawno się nie widzieliśmy.

A rough word-for-word breakdown is:

• dawno = a long time ago / for a long time
• się = reflexive/reciprocal marker
• nie = not
• widzieliśmy = we saw

So literally it is something like:

A long time, each other not saw-we.

That sounds strange in English, of course. The natural meaning is:

We haven't seen each other in a long time.

By itself, dawno often means long ago.

But in sentences like Dawno się nie widzieliśmy, it works more like:

not for a long time
or
it’s been a long time since...

So here it does not mean simply long ago in the English sense. It helps create the idea of it’s been a while.

Not exactly.

In this sentence, się does not mean ourselves. It helps form the expression widzieć się, which usually means:

• to see each other
• to meet

So widzieliśmy się means we saw each other.

This is very common in Polish: where English uses each other, Polish often uses a verb plus się.

Because Polish usually does not need a subject pronoun if the verb already shows who is doing the action.

The ending in widzieliśmy already means we.

So:

• widzieliśmy = we saw
• widziałem = I saw (male speaker)
• widziałeś = you saw (to a man)

You could add my for emphasis, but normally it is omitted:

• My dawno się nie widzieliśmy. = We really haven’t seen each other in a long time.

Because Polish does not have a direct tense equivalent to the English present perfect.

English says:

We haven’t seen each other in a long time.

Polish normally expresses that idea with a past tense form, plus context words like dawno or od dawna:

• Dawno się nie widzieliśmy.
• Nie widzieliśmy się od dawna.

So even though English uses have not seen, Polish uses a past form: nie widzieliśmy.

This is about aspect.

• widzieć is imperfective
• zobaczyć is perfective

In Dawno się nie widzieliśmy, Polish uses the imperfective because the sentence describes a situation over a stretch of time: we have not been seeing each other / we haven’t seen each other for a long time.

Using zobaczyć would suggest a single completed event, and it would not sound natural here.

Compare:

• Dawno się nie widzieliśmy. = We haven’t seen each other in a long time.
• Nie zobaczyliśmy się wczoraj. = We didn’t see each other yesterday / We failed to meet yesterday.

So for this sentence, widzieć się is the normal choice.

Yes, Polish word order is flexible.

The most natural version here is:

• Dawno się nie widzieliśmy.

You can also hear:

• Dawno nie widzieliśmy się.
• Nie widzieliśmy się od dawna.

All of these are understandable, but Dawno się nie widzieliśmy is a very common, natural way to say it.

A useful thing to remember is that się often appears early in the sentence, but it does not normally go at the very beginning.

In the Polish past tense, the plural form changes depending on gender.

• widzieliśmy = we saw, if the group is mixed or includes at least one male
• widziałyśmy = we saw, if the group is all female

So:

• Dawno się nie widzieliśmy. — said by a man, or by a mixed group
• Dawno się nie widziałyśmy. — said by a group of women, or by one woman speaking about herself and another woman

This is something English does not show, but Polish does.

Yes, very close.

• Dawno się nie widzieliśmy.
• Nie widzieliśmy się od dawna.

Both mean:

We haven’t seen each other in a long time.

The second version is a little more explicit because od dawna literally means something like for a long time now / since long ago.

For learners, Nie widzieliśmy się od dawna may feel easier to understand at first, but Dawno się nie widzieliśmy is extremely common and natural.

Yes — very common.

You can say it when you run into someone you have not seen for a long time. In that situation, it works a lot like:

• Long time no see
• We haven’t seen each other in ages

It is neutral and natural in everyday conversation. It is one of the most typical Polish phrases for that situation.