Együttműködünk, ugyanis sok lufi és girland kell.

Együttműködünk means we cooperate / we work together.

It is written as one word because it is a single verb in Hungarian: együttműködik = to cooperate / collaborate.

You can roughly see these parts in it:

• együtt = together
• működik = functions / works

But as a whole, együttműködik has the established meaning cooperate. The ending -ünk makes it we in the present tense:

• együttműködöm = I cooperate
• együttműködünk = we cooperate

Because Hungarian usually does not need subject pronouns when the verb ending already shows the subject.

Here, the ending -ünk already tells you it is first person plural: we.

So:

• Együttműködünk = We cooperate
• Mi együttműködünk = also possible, but mi is usually added only for emphasis or contrast

For example:

• Mi együttműködünk, nem ők. = We are cooperating, not they.

Here ugyanis means something like:

• because
• since
• after all
• you see

It introduces an explanation for what was just said.

So:

• Együttműködünk, ugyanis sok lufi és girland kell. = We’re cooperating, because/after all a lot of balloons and garlands are needed.

It often sounds a little more explanatory or slightly more formal/written than the plain everyday mert.

Both can often be translated as because, but they are not always used in exactly the same way.

• mert is the most basic, neutral word for because
• ugyanis gives an explanation or justification for the previous statement

So:

• Együttműködünk, mert sok lufi és girland kell. = very neutral because
• Együttműködünk, ugyanis sok lufi és girland kell. = a bit more like We’re cooperating, you see / after all / because...

A learner can safely think:

• mert = plain because
• ugyanis = explanatory because

Because in Hungarian, after numbers and quantity words, the noun is usually singular, not plural.

So Hungarian says:

• két könyv = two books literally two book
• sok ember = many people literally many person
• sok lufi = many balloons literally many balloon

That is completely normal in Hungarian.

So in this sentence:

• sok lufi és girland

both nouns stay in the singular form, even though English would normally use plurals.

Because with a quantity expression like sok lufi, Hungarian commonly uses singular agreement.

So:

• Sok lufi kell. = A lot of balloons are needed.
• Sok szék kell. = A lot of chairs are needed.

If you used a plain plural noun without a quantifier, then plural agreement would be more natural:

• Lufik kellenek. = Balloons are needed.
• Girlandok kellenek. = Garlands are needed.

So kell is normal here because the subject-like phrase is a quantified expression.

Yes, in this sentence it naturally applies to both nouns.

So sok lufi és girland kell is understood as:

• many balloons and garlands are needed

If the speaker wanted to be extra explicit, they could say:

• sok lufi és sok girland kell

But repeating sok is not necessary.

Because sok already functions as a quantifier.

In a general statement, Hungarian normally says:

• sok lufi = many balloons

not:

• a sok lufi

The version with a would usually mean something more specific, like:

• a sok lufi = the many balloons / those many balloons

So in this sentence, no article is the normal choice.

They are in the nominative form, the basic dictionary form.

Hungarian often expresses need with kell, which literally behaves more like is needed than like English need.

So:

• Sok lufi és girland kell. = literally A lot of balloons and garland is needed = natural English A lot of balloons and garlands are needed

If you want to say who needs them, Hungarian often uses the dative:

• Nekünk sok lufi és girland kell. = We need a lot of balloons and garlands. = literally To us, a lot of balloons and garlands are needed.

Yes, Hungarian word order is flexible, but changing it can change the focus or the feel of the sentence.

This version:

• Együttműködünk, ugyanis sok lufi és girland kell.

first states the main point we are cooperating, then gives the explanation.

A very natural alternative is:

• Együttműködünk, mert sok lufi és girland kell.

If you want to start with the reason, you could say something like:

• Sok lufi és girland kell, ezért együttműködünk. = A lot of balloons and garlands are needed, so we are cooperating.

So yes, the order can change, but not always without changing emphasis.

Because ugyanis introduces an explanatory clause, and in Hungarian that is normally separated with a comma.

So:

• Együttműködünk, ugyanis sok lufi és girland kell.

The comma helps show that the second part explains the first part.

This is similar to how English often separates explanatory clauses with punctuation, although the exact comma rules are not always identical.

A rough English-friendly guide would be:

• edj-üt-mű-kö-dünk

with the stress on the first syllable, because Hungarian normally stresses the first syllable of the word.

A few sound notes:

• gy is a soft consonant, somewhat like the sound in British duke or during
• ü / ű are front rounded vowels; English does not have exact matches
• ö is similar to German ö or French eu in peu

Also, vowel length matters:

• ü and ű are not the same
• the accent marks in Hungarian are important for pronunciation and meaning