גם היא מתלבשת מוקדם, כדי שלא תאחר כשהאורחים הראשונים יגיעו.

גם היא means she too / she also.

Starting with גם gives a slight emphasis to the idea that she is included too, probably along with other people already mentioned.

• גם היא מתלבשת מוקדם = She too gets dressed early
• היא גם מתלבשת מוקדם is possible, but the emphasis is a little different

In this sentence, גם היא is the more natural way to highlight she too.

מתלבשת is the present tense, feminine singular form of להתלבש, which means to get dressed / to dress oneself.

So:

• להתלבש = to get dressed
• מתלבש = getting dressed / gets dressed (masculine singular)
• מתלבשת = getting dressed / gets dressed (feminine singular)

Because the subject is היא (she), the feminine form מתלבשת is used.

Hebrew often uses להתלבש when talking about getting dressed, not just the fact of wearing clothes.

So:

• ללבוש = to wear / put on
• להתלבש = to get dressed / dress oneself

In this sentence, the idea is that she is getting dressed early, so מתלבשת is the right choice.

Because מוקדם here is being used as an adverb, meaning early, not as an adjective describing a feminine noun.

Hebrew very often uses the masculine singular form of an adjective as an adverb:

• לקום מוקדם = to get up early
• לבוא מוקדם = to come early
• להתלבש מוקדם = to get dressed early

So מוקדם does not agree with היא here. It is not saying she is early as an adjective; it is saying she does the action early.

כדי means in order to / so that.

שלא means that not / so not.

Together, כדי שלא means:

• so that ... not
• in order that ... not
• more naturally in English, so that she won’t...

So:

• כדי שלא תאחר = so that she won’t be late

This whole part gives the purpose of getting dressed early.

Because this is a full clause, not just a simple infinitive.

Compare:

• כדי לא לאחר = in order not to be late
• כדי שלא תאחר = so that she won’t be late

In כדי שלא תאחר, the verb is a finite verb (תאחר), so Hebrew uses שלא.

A useful way to think of it:

• לא often goes with infinitives
• שלא often introduces a clause with a conjugated verb

After כדי ש... / כדי שלא..., Hebrew normally uses the future tense to express the intended result or purpose.

So:

• כדי שלא תאחר = so that she won’t be late

Even though English may use different wording, Hebrew commonly uses the future here because it refers to something that is supposed to happen or not happen later.

From the context.

תאחר can grammatically be:

• she will be late (3rd person feminine singular)
• you will be late (2nd person masculine singular)

But the sentence already has היא, so the intended meaning is clearly she will be late.

This kind of form overlap is common in Hebrew, and context usually makes the meaning clear.

Because in Hebrew, after כש (when) referring to a future event, the verb is usually in the future tense.

So Hebrew says:

• כשהאורחים הראשונים יגיעו

Literally this looks like when the first guests will arrive, but that is just how Hebrew expresses it. In natural English, we normally say:

• when the first guests arrive

So this is a normal Hebrew-English difference.

Because כש־ (when) is a prefix-like conjunction that attaches to the following word.

So:

• כש + האורחים becomes כשהאורחים

This is very common in Hebrew with short connecting words like ש־, כ־, ו־, ל־, etc.

This means the first guests.

A few things are happening:

1. אורחים = guests
2. ראשונים = first (masculine plural)
3. Both are definite, so both get ה־:
   • האורחים = the guests
   • הראשונים = the first

In Hebrew, adjectives agree with the noun in:

• gender
• number
• definiteness

So:

• אורחים ראשונים = first guests
• האורחים הראשונים = the first guests

יגיעו is the future tense, 3rd person masculine plural form of להגיע, meaning to arrive / to reach.

So:

• להגיע = to arrive
• יגיע = he will arrive
• יגיעו = they will arrive

Since האורחים is plural, יגיעו is the correct form.

Because it matches האורחים, which is a masculine plural noun.

Hebrew adjectives must agree with the noun they describe.

So here:

• אורח = guest
• אורחים = guests
• ראשון = first (masculine singular)
• ראשונים = first (masculine plural)

That is why the sentence uses הראשונים and not a feminine form like הראשונות.