היה לנו כיף במסיבה.

Because Hebrew is not phrasing this as we being the grammatical subject in the same way English does.

Literally, the structure is closer to:

there was fun to us at the party

So:

• היה = there was / it was
• לנו = to us / for us
• כיף = fun

In this kind of sentence, לנו expresses the people experiencing something, and היה often stays in the masculine singular form because it matches the idea of an impersonal there was construction.

So even though the natural English translation is we had fun, the Hebrew grammar is built differently.

לנו means to us or for us.

It is made of:

• ל־ = to / for
• נו = us

In Hebrew, expressions about having something or experiencing something often use ל־ plus a pronoun:

• יש לי זמן = I have time (literally there is time to me)
• היה לנו כיף = we had fun (literally there was fun to us)

So לנו is the part that gives the meaning we in natural English translation.

Here כיף is functioning like a noun meaning fun.

So היה לנו כיף means something like:

• it was fun for us
• we had fun

In modern Hebrew, כיף is a very common everyday word. It can also appear in other expressions, for example:

• זה כיף = that’s fun / that’s nice
• היה כיף = it was fun

It is a very natural word in spoken Hebrew.

Hebrew often uses a different structure from English here.

English commonly says:

• We had fun
• We enjoyed the party

Hebrew very naturally says:

• היה לנו כיף במסיבה = we had fun at the party

Another common Hebrew option is:

• נהנינו במסיבה = we enjoyed ourselves at the party
• נהנינו מהמסיבה = we enjoyed the party

So היה לנו כיף is not strange at all—it is one of the most common everyday ways to express this idea.

במסיבה means at the party.

It is made from:

• ב־ = in / at
• המסיבה = the party

When ב־ is attached to a noun with ה־ (the), the two usually combine:

• ב + המסיבה → במסיבה

This is a very common Hebrew pattern:

• בבית = in the house
• בשיעור = in class / in the lesson
• במסיבה = at the party

So it is one written word because Hebrew commonly attaches prepositions directly to nouns.

It actually does have the meaning of the party, but the ה־ is absorbed into the preposition.

Compare:

• מסיבה = a party
• המסיבה = the party
• במסיבה = at a party or at the party, depending on context
• במסיבה can specifically come from ב + המסיבה

In many cases, context tells you whether English should use a or the.

In this sentence, the intended meaning is usually at the party.

It is very natural everyday Hebrew and slightly conversational in tone because of the word כיף.

It is completely normal and common in speech. You might also see or hear:

• נהנינו במסיבה = a bit more neutral/formal
• היה לנו מאוד כיף במסיבה = we had a lot of fun at the party
• המסיבה הייתה כיפית = the party was fun

So היה לנו כיף במסיבה is standard and common, especially in spoken Hebrew.

Yes. Hebrew word order is more flexible than English.

The sentence:

• היה לנו כיף במסיבה

could also appear as:

• במסיבה היה לנו כיף

Both mean essentially the same thing.

The difference is mostly about emphasis:

• היה לנו כיף במסיבה = neutral, straightforward
• במסיבה היה לנו כיף = puts more emphasis on at the party

So the original order is natural, but it is not the only possible one.

No, not in standard usage.

You say:

• היה לנו כיף

not

• הייתה לנו כיף

That is because כיף is treated as masculine singular in this expression, so the verb appears as היה.

You can compare:

• היה לנו זמן = we had time
• היה לנו מזל = we were lucky / we had luck
• היה לנו כיף = we had fun

If the noun were feminine singular, then the verb would change:

• הייתה לנו בעיה = we had a problem

If it were plural:

• היו לנו בעיות = we had problems

A common pronunciation is:

ha-YA la-NU kef ba-msi-BA

More carefully:

• היה = ha-YA
• לנו = la-NU
• כיף = kef
• במסיבה = ba-msi-BA

The main stresses are usually on:

• היה
• לנו
• במסיבה

And כיף is a short one-syllable word.

Yes. A useful literal gloss is:

• היה = there was / it was
• לנו = to us
• כיף = fun
• במסיבה = at the party

So the sentence is roughly:

There was fun for us at the party

That is not natural English, but it helps explain the Hebrew grammar. Once you understand that pattern, sentences like this become much easier to recognize.