W weekend spotykamy się z kuzynem i kuzynką na obiedzie u babci.

In Polish, the present tense of an imperfective verb is often used to talk about future arrangements, especially when there is a time expression like w weekend (on/over the weekend).

• W weekend spotykamy się…
  literally: On the weekend we meet…
  but in context = We’re meeting… / We will be meeting… (this weekend)

This is similar to English:

• We meet them on Saturday = We’re meeting them on Saturday.

So:

• spotykamy się (present, imperfective) + w weekend (future time)
  → natural way to talk about a planned future meeting.

The reflexive pronoun się is essential here.

• spotykać się z kimś = to meet (up) with someone / to get together with someone (mutual, arranged).
• spotykać kogoś (without się) = to meet someone, encounter someone (regularly), often not so mutual-sounding, more like “to see someone (as part of your life)”.

Examples:

• Często spotykamy się z przyjaciółmi.
  We often meet up with friends.
• Często spotykam tego sąsiada w sklepie.
  I often bump into that neighbor in the shop. (no się)

In your sentence, it’s a mutual meeting, so you must say:

• spotykamy się z kuzynem i kuzynką
  not: spotykamy z kuzynem i kuzynką (ungrammatical).

z kuzynem and z kuzynką are in the instrumental case.

When z means “with”, it normally takes the instrumental:

• z kim? z czym? (with whom? with what?)

So:

• kuzyn (cousin, m.) → z kuzynem (instr. sg.)
• kuzynka (cousin, f.) → z kuzynką (instr. sg.)

This is the standard pattern:

• z mamą (with mom), z kolegą (with a (male) colleague), z siostrą (with (my) sister).

They have different endings because they are different genders, and the instrumental case endings depend on gender:

• kuzyn – masculine noun

  • Nominative: kuzyn
  • Instrumental: kuzynem (‑em)

• kuzynka – feminine noun

  • Nominative: kuzynka
  • Instrumental: kuzynką (‑ą)

Typical instrumental singular endings:

• Masculine: ‑em (kolega → kolegą; nauczyciel → nauczycielem)
• Feminine: ‑ą (siostra → siostrą; babcia → babcią)

Both are grammatically correct:

• z kuzynem i kuzynką
• z kuzynem i z kuzynką

In practice:

• z kuzynem i kuzynką is more common and sounds natural and smooth.
• z kuzynem i z kuzynką can add a tiny bit of emphasis on each person separately, but often it just sounds slightly heavier.

Polish frequently lets one preposition govern a whole list:

• z mamą, tatą i bratem (with mom, dad and brother).

w weekend uses the accusative case, but for inanimate masculine nouns (like weekend), the accusative form = the nominative form, so you see no visible change.

Why accusative?
With expressions of time like “on Monday, in May, at 5 o’clock” etc., Polish very often uses preposition + accusative:

• w poniedziałek (on Monday – accusative)
• w przyszły piątek (this coming Friday – accusative)
• w weekend (on/over the weekend – accusative)

You might also hear w weekendzie (locative), but:

• w weekend is more common and more colloquial, especially in modern speech.
• w weekendzie can sound more old-fashioned or regional; it’s correct but less frequent.

So w weekend is what you’ll usually say.

Both exist, but they mean different things:

• na obiedzie – locative case, means at (the) lunch / during lunch, i.e. location / situation
  → We’re meeting (while we are) at lunch / at Grandma’s for lunch.

• na obiad – accusative case, means for lunch in the sense of direction / goal
  → We’re going (to someone) for lunch.

Compare:

• Jesteśmy na obiedzie u babci.
  We are at lunch at Grandma’s (house).

• Idziemy do babci na obiad.
  We’re going to Grandma’s for lunch.

In your sentence:

• spotykamy się … na obiedzie
  focuses on where / in what situation you’re meeting: at the lunch.

1. Case and form:

   • The preposition u (at someone’s place) takes the genitive case.
   • babcia (grandma) – genitive singular: babci
     So you must say u babci, not u babcia.

2. Meaning difference:

   • u babci = at Grandma’s place (location)
   • do babci = to Grandma’s (place) (movement / direction)

So:

• na obiedzie u babci = at lunch at Grandma’s (house).
• Idziemy do babci na obiad. = We’re going to Grandma’s for lunch.

In Polish, subject pronouns (ja, ty, on, my, wy, oni/one) are often dropped because the verb ending already shows the person and number.

• spotykamy się → the ending ‑my tells you it’s “we”.
• Adding my (my spotykamy się…) is usually only for emphasis or contrast:
  • My spotykamy się z kuzynem, a oni zostają w domu.
    We are the ones meeting with the cousin, and they are staying at home.

So in neutral sentences, you normally omit the pronoun:

• Spotykamy się z kuzynem… = We’re meeting with (our) cousin…

Yes. Polish word order is fairly flexible, especially in spoken language, as long as the grammar (cases, prepositions, endings) is correct.

All of these are possible and natural:

• W weekend spotykamy się z kuzynem i kuzynką na obiedzie u babci.
• Spotykamy się w weekend z kuzynem i kuzynką na obiedzie u babci.
• W weekend u babci spotykamy się z kuzynem i kuzynką na obiedzie.

Differences are mostly about rhythm and emphasis, not about basic meaning.
The original version (W weekend spotykamy się…) is a very neutral, common pattern:

• [Time] + [Verb] + [With whom] + [Where].

They differ in aspect and nuance:

• spotykać się (imperfective) → spotykamy się

  • Focus on the process, a plan, or a habit.
  • Can mean we are meeting (this time) or we (usually) meet.

• spotkać się (perfective) → spotkamy się (future)

  • Focus on the completed event, a single concrete meeting.
  • Clearly future: we will (have a) meet(ing), we’ll meet.

Both can work with w weekend, but:

• W weekend spotkamy się z kuzynem…
  sounds like a specific one-time future event, slightly more “single occasion”.
• W weekend spotykamy się z kuzynem…
  sounds like either a planned meeting or even a typical weekend habit, depending on context.

In casual speech, for a planned meeting, both are common, with a subtle difference in feel rather than meaning.

Polish always marks gender for “cousin” in the normal words:

• kuzyn – male cousin
• kuzynka – female cousin

If you really need to be vague, people normally rely on context or say something like:

• jeden z kuzynów (one of my cousins – but masculine plural form).
• z kuzynostwem (with the cousins as a group – collective, but not for one person).

For one specific cousin, you usually have to choose kuzyn or kuzynka once the gender is known.

You can adapt the sentence like this:

• W weekendy spotykamy się z kuzynami na obiedzie u babci.
  = On weekends / Every weekend we meet with (our) cousins for lunch at Grandma’s.

Alternatives:

• Co weekend spotykamy się z kuzynami na obiedzie u babci.
  Every weekend we meet with (our) cousins for lunch at Grandma’s.

Notes:

• w weekendy or co weekend – express regularity.
• kuzyni / kuzynami – plural of kuzyn (mixed or all-male group).
  Instrumental plural: z kuzynami.
  (If the group is all female, you could say z kuzynkami.)