Learn Hardcore Polish: Na ścianie nad biurkiem wisi kalendarz z rodzinnych wakacji. - On the wall above the desk there is a calendar from a family holiday.

The base noun is ściana (a wall) – nominative singular.
After the preposition na meaning “on / on top of” in a static location, Polish uses the locative.
Feminine noun ściana in the locative singular becomes ścianie.

So:

na ścianie = on the wall (location, no movement)
If you were expressing movement onto the wall, you’d use na ścianę (accusative).

Why is it nad biurkiem and not nad biurko or nad biurkiem vs nad biurkiem with a different ending?

Biurkiem is in the instrumental case (singular, neuter).

The base noun is biurko (desk) – nominative singular.
The preposition nad (“over / above”) takes:
- instrumental for location (where something is),
- accusative for movement (where something is moving to).

Here it’s a fixed location (the calendar is hanging above the desk), so we use instrumental:

nad biurkiem = above the desk (no movement)

If you said He is putting the picture up above the desk, it would be:

nad biurko (accusative: movement toward a position).

Why is the verb wisi used here? Could I just say jest instead?

Wisi is the 3rd person singular of wisieć = to hang (to be hanging).

Wisi kalendarz literally: a calendar hangs.
It emphasizes the manner/position: the calendar is in a hanging position.

You can say:

Na ścianie nad biurkiem jest kalendarz z rodzinnych wakacji.

This is grammatically correct but more neutral: it just states there is a calendar there, without highlighting how it’s placed. Wisi sounds more natural when talking about objects like pictures, calendars, lamps, etc., that are actually hanging.

There’s no “a/the” in kalendarz. How do I know if it means a calendar or the calendar?

Polish has no articles (no a, an, the), so kalendarz by itself can correspond to:

a calendar
the calendar

Which one is correct depends on context, not on any special word in the sentence. Here, in normal usage, you would usually understand it as the calendar (we both know which one) because it’s specified further by z rodzinnych wakacji (from the family holidays), making it a particular calendar.

What does z in z rodzinnych wakacji mean here, and which case does it require?

In this context, z means “from” (not “with”).

With the meaning “from (a place/time/event)”, z takes the genitive case.
So we get z + genitive plural: z rodzinnych wakacji = from (our) family holidays.

Compare:

z wakacji – from the holidays
z rodzinnych wakacji – from the family holidays

Note that z can also mean “with”, but then it takes the instrumental:

z kolegą – with a friend (instrumental)
z rodzinnych wakacji – from family holidays (genitive)

Why is it rodzinnych wakacji and not rodzinne wakacje?

Because the phrase z rodzinnych wakacji is in the genitive plural, and both the adjective and noun must agree in case, number, and gender.

Base forms:
- rodzinny – family (adjective)
- wakacje – holidays/vacation (plural only, treated as plural feminine in practice)
After z = “from”, we need genitive plural:
- wakacje → wakacji (genitive plural)
- rodzinne → rodzinnych (genitive plural adjective form)

So:

rodzinne wakacje – nominative/accusative plural (family holidays as the subject or direct object)
z rodzinnych wakacji – genitive plural (from family holidays).

Why is wakacji used instead of wakacje? Is that also a case change?

Yes. Wakacji is the genitive plural of wakacje.

Nominative plural: wakacje – holidays
Genitive plural: wakacji – used after certain prepositions, including z meaning “from”.

So:

Lubię wakacje. – I like holidays. (accusative = nominative form)
Wracam z wakacji. – I’m coming back from holidays. (genitive plural after z)

In your sentence, z rodzinnych wakacji uses that same genitive plural form.

Is the word order fixed? Can I say Kalendarz z rodzinnych wakacji wisi na ścianie nad biurkiem instead?

You can absolutely say:

Kalendarz z rodzinnych wakacji wisi na ścianie nad biurkiem.

Both versions are correct:

Na ścianie nad biurkiem wisi kalendarz z rodzinnych wakacji.
Kalendarz z rodzinnych wakacji wisi na ścianie nad biurkiem.

Polish word order is relatively flexible, especially for things like:

emphasizing what is new/important information
organizing the sentence to sound more natural in context

Version 1 starts with where (on the wall above the desk), then tells you what is there.
Version 2 starts with what (the calendar) and then tells you where it is. Which one is preferred depends on what you’re emphasizing in the conversation or narration.

What cases are used in this sentence, and can you summarize them?

The sentence uses three different cases:

Na ścianie – locative singular
- Noun: ściana (fem.) → ścianie
- After na with a static location (“on” somewhere).
Nad biurkiem – instrumental singular
- Noun: biurko (neut.) → biurkiem
- After nad with a static location (“above” something).
z rodzinnych wakacji – genitive plural
- Noun: wakacje (pl.) → wakacji
- Adjective: rodzinne (pl.) → rodzinnych (pl. gen.)
- After z meaning “from”.

The subject kalendarz is in the nominative singular (basic dictionary form, masculine inanimate).

How does the adjective rodzinny change with wakacje in different cases?

For wakacje (plural), treating them as plural non-masculine, here are the most common forms with rodzinny:

Nominative: rodzinne wakacje – family holidays (subject)
Accusative: rodzinne wakacje – family holidays (direct object)
Genitive: rodzinnych wakacji – of/from family holidays
Dative: rodzinnym wakacjom – to/for family holidays
Instrumental: rodzinnymi wakacjami – with/by family holidays
Locative: rodzinnych wakacjach – about/in family holidays

In your sentence we use genitive plural: z rodzinnych wakacji.

Could I say kalendarz rodzinnych wakacji instead of kalendarz z rodzinnych wakacji?

You can, but there is a nuance:

kalendarz z rodzinnych wakacji
– literally: a calendar from family holidays
– strongly suggests the calendar is a souvenir or was made using photos from that trip.
kalendarz rodzinnych wakacji
– literally: a calendar of family holidays
– sounds more like a calendar whose topic is family holidays, more abstractly (for example, a calendar listing all your family trips).

In everyday speech about a photo calendar you brought back or made from holiday photos, kalendarz z rodzinnych wakacji is more natural.

What’s the difference between nad and na in this context? Could I say na biurkiem or nad ścianą?

In this context:

na = on (a surface), in contact with it.
- na ścianie – on the wall (attached/hanging on the wall)
nad = above / over, not in contact with the thing.
- nad biurkiem – above the desk (in the space above it)

You normally cannot say:

na biurkiem – wrong combination of preposition and case, and semantically odd here.
nad ścianą – would mean above the wall (somewhere higher than the wall itself), which is not what we want; the calendar is on the wall, not floating above the wall.

So the natural pairing in this sentence is:

na ścianie (on the wall)
nad biurkiem (above the desk).