ברגע שמסיבת ההחלפות מתחילה, אנחנו ממיינות את הבגדים.

In this sentence, ברגע ש־... means as soon as ... or the moment that ....

• ב־ = in / at
• רגע = moment

So ברגע שמסיבת ההחלפות מתחילה is literally something like at the moment that the swap party begins, but in natural English it usually means as soon as the swap party starts.

A very common pattern in Hebrew is:

• ברגע ש... = as soon as...
• ברגע שאני מגיעה... = as soon as I arrive
• ברגע שזה נגמר... = as soon as it ends

The ש־ is a very common Hebrew connector meaning that.

Here it connects ברגע to the clause that follows:

• ברגע ש... = the moment that... / as soon as...

So:

• ברגע שמסיבת ההחלפות מתחילה = as soon as the clothing-swap party starts

In speech and writing, ש־ often attaches directly to the next word, which is why you see שמסיבת as one written unit.

This is because Hebrew is using a construct chain (called סמיכות), which is a very common way to say X of Y.

• מסיבה = party
• מסיבת = party of ...
• החלפות = swaps / exchanges
• מסיבת ההחלפות = the swap party or literally the party of the swaps

When a noun comes before another noun in this structure, the first noun often changes form. That is what happens here:

• מסיבה → מסיבת

Compare similar examples:

• עוגה = cake → עוגת שוקולד = chocolate cake
• תחנה = station → תחנת רכבת = train station

So מסיבת ההחלפות is completely normal Hebrew grammar.

Because the subject is מסיבת ההחלפות, and the main noun there is מסיבה, which is feminine singular.

So the verb must agree with it:

• מסיבה מתחילה = the party starts

That is why you get מתחילה and not:

• מתחיל (masculine singular)
• מתחילים (masculine plural)
• מתחילות (feminine plural)

Even though החלפות is plural, it is not the grammatical head of the phrase. The head noun is מסיבה, so the verb agrees with מסיבה.

Both mean we sort, but they differ by gender:

• אנחנו ממיינים = we sort when the speakers are male or a mixed-gender group
• אנחנו ממיינות = we sort when the speakers are all female

Hebrew present-tense verb forms agree with the subject in gender and number. Since the sentence uses ממיינות, it tells you that we refers to a group of females.

This is something English does not show, so it often stands out to learners.

ממיינות comes from the verb למיין, which means to sort, to classify, or to organize into categories.

Here:

• למיין = to sort
• ממיינות = sorting / sort (for we, feminine plural)

So:

• אנחנו ממיינות את הבגדים = we sort the clothes

This is present tense in Hebrew, but Hebrew present tense can often sound like either:

• we sort the clothes
• we are sorting the clothes

depending on context.

את here is the direct object marker. It is used before a definite direct object.

• הבגדים = the clothes
• because it is definite (it has ה־, the), Hebrew uses את

So:

• ממיינות את הבגדים = sort the clothes

Compare:

• אני קוראת ספר = I am reading a book
  no את, because ספר is indefinite

• אני קוראת את הספר = I am reading the book
  את appears because הספר is definite

Important: this את is not translated into English. It is grammatical, not meaningful by itself here.

The noun בגד means garment or piece of clothing.

Its plural is:

• בגדים = clothes / garments

This word is grammatically masculine plural, even though in English clothes does not feel especially countable or gendered.

Here:

• הבגדים = the clothes

with ה־ meaning the.

So the final part of the sentence is simply:

• את הבגדים = the clothes (as a direct object)

Yes. The verbs are in the present tense:

• מתחילה = starts / is starting
• ממיינות = sort / are sorting

In Hebrew, the present tense can describe:

1. something happening right now

   • The party is starting, and we are sorting the clothes

2. a habitual or repeated action

   • Whenever the swap party starts, we sort the clothes

Because of ברגע ש־, this sentence can naturally sound like a regular procedure or routine: As soon as the swap party starts, we sort the clothes.

Yes, Hebrew has some flexibility in word order, though the given version is very natural.

The original sentence:

• ברגע שמסיבת ההחלפות מתחילה, אנחנו ממיינות את הבגדים.

A possible variation:

• אנחנו ממיינות את הבגדים ברגע שמסיבת ההחלפות מתחילה.

Both are grammatical. The difference is mostly about emphasis:

• starting with ברגע... highlights the timing first
• starting with אנחנו... highlights who is doing the action first

The original version sounds very natural if you want to frame the action as part of a sequence: As soon as the party starts, we sort the clothes.

The main change would be the verb ממיינות.

If the group is:

• all female → אנחנו ממיינות
• all male or mixed gender → אנחנו ממיינים

So you would get:

• ברגע שמסיבת ההחלפות מתחילה, אנחנו ממיינים את הבגדים.

Everything else stays the same, because מסיבת ההחלפות is still feminine singular, so מתחילה does not change.

A simple pronunciation guide would be:

be-RE-ga she-me-si-BAT ha-ha-kha-la-FOT mat-KHI-la, a-NACH-nu me-mai-NOT et ha-bga-DIM

A few helpful notes:

• ח in החלפות and מתחילה is a throaty sound, not like English h
• the stress is roughly on:
  • רֶגַע → RE-ga
  • מסיבת → si-BAT
  • החלפות → la-FOT
  • מתחילה → KHI-la
  • ממיינות → NOT
  • בגדים → DIM

If you want, I can also break the whole sentence down word by word with transliteration and grammar labels.